The Braun KM32 MIXING HEAD ("drive arm") is actually a "gear case" housing mostly metal gears, but there are also two nylon worm-gears inside. The gear case is lubricated with about 4-1/2 ounces of what I believe to be food-safe mineral oil. The underside of the MIXING HEAD has four oil-seals that potentially can leak. The two "large oil-seals" are for the two shafts that drive the wisk and the dough hook. These can be replaced with out disassembly of the MIXING HEAD. The remaining two "small oil-seals" seal the bowl drive gear shaft and the high speed input shaft. Partial disassembly of the MIXING HEAD is required to expose these two "small oil seals" before they can be replaced. New oil-seals are hard to come by, because Braun U.S. is no longer a source for these parts. Some NOS stock may appear from time to time. I have a set of four available on eBay as of 3.20.2011 (search for "Braun KM32" and you will see them). For the "large oil-seals" just Google, "how to replace a shaft oil-seal" to learn how to do this. Disassembly of the MIXING HEAD to get access to the "small oil-seals" is another matter. The white "bakelite" type material used for the mixing head COVER is lustrous and beautiful, but also brittle and easily damaged. It is not a flexible thermoplastic. Avoid prying against it with metal tools. Two deeply recessed screws, on the input end of the MIXING HEAD must be removed to loosen the "big end" of the WHITE COVER. Then lift the big end of the WHITE COVER about 3/16" of an inch or so, and move it forward, to get it to disengage from the small end of the metal GEAR CASE. It the locking lever is in the way, either loosen the two screws holding it, or remove it. Once the WHITE COVER is removed, the metal GEAR CASE COVER screws will be exposed. Next remove the metal GEAR CASE COVER, then drain and save the gear oil (invert in a clean pan for several hours). Four screws inside the GEAR CASE must now be removed to free the entire "worm gear drive train" it can be lifted up and out as one unit, but only if you have some one rotate the mixing head INPUT COUPLING while you lift (reverse direction if at first it will not budge). It is easy for fiber washers and thrust washers to be left behind, so one must take their time and notice exactly where everything goes (or went!). The cross pin holding the shaft for the BOWL DRIVE GEAR SHAFT must be removed before the BOWL DRIVE GEAR SHAFT can be removed from the MIXING HEAD. The cross pin nests in a slot in the nylon worm-gear on this shaft, as I recall. Now, at the input end of the metal GEAR CASE....to remove the INPUT COUPLING you will first need to protect the opposite end of the INPUT WORM SHAFT so that you do not mar it while holding it. A piece of tubing or shim stock could be used to protect it. Then place an old drill chuck over the protected end, and close the chuck until it is tight. Now holding this end firmly with one hand, turn the INPUT COUPLING clock-wise to unthread it from the INPUT WORM SHAFT (you are dealing with a "left-hand thread" here!). Now the small oil-seal for this INPUT WORM SHAFT will be exposed. Final caution: When you are all done, and ready to re-attach the white cover, I suggest that you DO NOT TIGHTEN the two deep-recessed screws. Instead, just snug is good, thus protecting the screw bosses on the underside of the white cover from damage. This all sounds more complicated than it is, but make no mistake about it, there is a learning curve. Expect some setbacks.
boxertwinman, March 2011
