Diverter Valve
Welcome to the wonderful world of twin tub washing! You look to have a very nice set there in Avocado no less. This diverter as Andy said is still readily available, finding one locally I found can be hard. Parts dealers here have been to crap for me though. For what it's worth, it's also the same valve that Maytag used on Suds Saver full-size models.
This valve setup is also somewhat unusual on the Maytag as it's not just a "let the wash tub drain" (for lack of a better term) setup as in Hoovers and the Japanese washers, but it will only drain from one OR the other, not both. On most twin tub machines, the spinner side is always open to the pump and the drain control opens up the wash side, but not here. So you have to be somewhat careful there the water is spun out of the load before draining the wash tub. The reason for the broken flapper is that the core of it is made from cheap pot metal. There is always water in this part of the system, usually soapy water because few people seem to ever rinse them out when they're done. Over time the cheap metal just weakens and erodes away until poof, gone. This is one of those parts they should have made from plastic years ago, but alas. When you reinstall it, you will need to adjust the cable as that no water bleeds over to the other tub. Fill the washer tub with some water and observe the level and the presence of water in the spinner. On your machine, which is an early one, there are 4 screws that hold on the plate with the cable wheel that need to be adjusted. When the screws are loose the plate can be slid up and down for adjustment. You just have to fiddle with it to get it where you want it.
Also, as Kevin mentioned, check the "poly-belts" on both of the machines. The washer uses a clear polyurethane belt to drive the impellers, and this is the most common failure on these washers. Replacements are hard to find, but Martin (Yogitunes) has had luck with using other replacement materials for that belt (which he could sell and make $$$, hint hint). The dryer also uses one of these belts for the blower, so if it powers up and heats and tumbles but no air out the back, then this is why.
All in all they look nice, and I hope you get years of enjoyment from them!
-Tim
(see, I really am back...)
