Further to my previous answer, I have now fixed the defective interlock. This may not be applicable to you as you still had a problem after replacing your interlock. I would advise you to make sure that your wiring connectors are correctly replaced and that there are no bad connections also at the other end of the various wires coming from the interlock eg where they connect to the PCB at the top front of the machine (assuming the PCB location is the same for your FS1355W as for my FS1555W).
Here's what I fixed on my interlock. Make lots of sketches and notes if you do this. After removing the cover from the interlock by (releasing the four clips) I noticed scorch marks below the bimetalic strip where it contacts the 1000 ohm resistance "heater". This is located unter the contact strip (later called CS) which is secured to the plastic case by a brass rivet. The resistor is a grey ceramic disk about 7mm dia by 3mm thick. The bimetalic strip was not making adequate contact with the resistor and it was sparking causing burning and occasional faint flickering of the "door locked" lamp. Another problem I had was that the bimetalic strip appeared to be bent too far down such that even when the strip did curve up when heated, it didn't force the contact strip (CS) far enough up to make good contact with the contact point on the metal strip which forms connector 5 (all this at the opposite end from the rivet). After sketching the layout of the components and taking a few digital photos I removed the white plastic wheel (about 20mm dia) which controls the locking of the door. You may need to manually operate the solenoid coil plunger several times to rotate the wheel until the key slot is in line with a tiny pin. The wheel then lifts off. Remove the spring, the white plastic ratchet pin and the black plastic component which is pushed by the solenoid plunger. Next you should remove the metal strip which forms connector 5 of the interlock. Next, carefully drill out the rivet which will then allow you to gently remove the bimetalic strip, the contact strip (CS) above it, the small black plastic locking pin (this pin is what locks the door). Note that you will also have to gently lift out the solenoid coil and its connector strip as these are all soldered to the contact strip/bimetalic strip assembly. Don't lose the small (50 ohm?) resistor which is associated with the solenoid coil connector strip. It looks identical to the 1000 ohm resistor mentioned above so don't get them mixed up. You should now clean both sides of the 1000 ohm resistor as they may have scorch deposits on them. Next you should gently pull out the bimetalic strip from under the contact strip (CS), (no longer riveted together), noting carefully which way is up and which is down for the bimetalic strip. The next part sounds complicated but the purpose is to improve the contact between the underside of the bimetalic strip and the top of the 1000 ohm resistor. I did two things for this. First take a center punch and gently make a dent in the top of the bimetalic strip at a location such that its underside will have a point contact with the resistor rather than a "flat" contact. Next bend the bimetalic strip downwards a few degrees starting about five mm from the center of the rivet hole. Next it is necessary to bend the bimetalic strip back up slightly, starting a few mm further on from the punched dent (on the opposite side of the dent from the rivet hole). This will narrow (after assembly) the gap between the contact point on the contact strip (CS) and the contact point on the metal strip which forms connector 5. Now reassemble as follows. Place the 1000 ohm resistor back in its recess. Gently push the bimetalic strip back into its location below the contact strip (CS) making sure it is the correct way up. Place the small plastic locking pin on the end of (CS) and replace the complete contact strip/solenoid coil back into the plastic housing making sure that you first place the plunger back into the coil! Ensure that the (50 ohm?) resistor is in place. When all these components (including the connector 5 metal strip) have been pushed firmly into place, use a small bolt or countersunk screw and nut to replace the original rivet. The screw should go in from below and the nut applied on the contact strip (CS). Make sure the screw is short enough to allow the plastic cover to go back onto the interlock. Next check that there is a small gap between the contact points on (CS) and connector 5 metal strip. If they are touching you can use two small screwdrivers to bend the bimetalic strip down slightly so you have a gap. Take care not to lose the strong contact force between the bimetalic strip and the 1000 ohm resistor. Don't forget that when the plastic cover is replaced, it will force the contact point on connector 5 down closing the gap with the contact point on (CS). I used a multimeter to check that the points were open while pushing down with a screwdriver to simulate the pressure of the plastic cover on the top contact point. Next reassemble the white plastic (20mm dia) wheel, the white plastic ratchet pin, the black plastic component which is pushed by the solenoid plunger and the spring. To ensure the solenoid plunger could operate the wheel ok I then manually operated the solenoid plunger sufficient times to rotate the wheel exactly a full revolution back to where the key slot was in line with the tiny pin (I thought that this was likely to be the correct starting position). Next replace the plastic cover and the connecting wires. Don't think I've forgotten anything. Use common sense throughout and don't just blindly follow this which is from memory. I checked that everything appeared to work ok before re-installing the interlock on the door, you can use a screwdriver to move the metal locking plate to the locked position. When power is applied the plunger should then give two clicks and the lock and lamp should be on.
Please let me know if this helped and if it solved your problem. I put a lot of work into this answer and would appreciate acknowledgement here on this Q and A session and/or an e-mail to mooreaj01@yahoo.com
Alan, November 2005
