In order to get to the power cord connections, the mixer needs to be substantially disassembled. This involves:
Removing the head from the base (stand), then --
taking off the rear cover, drip ring, planetary, the 9 screws holding the halves of the head together, separating the halves, removing the rear bearing housing ....
If you are comfortable doing the above, and a bit more, look up and join (free) WACEM where you can find the original Service Manual for the K-5A plus a bunch of photos of your era machine's interior.
You can also ask more questions there and get answers from knowledgeable folks.
John, October 2015