There is actually a service pointer out on this problem. That document is attached. Have they looked at the date code on the parts they are replacing? This is a fairly new document and they may not know about it yet.

I would investigate the date code on the timers they have been installing before modifying the timing circuit, especially since this is a known issue and one that is covered under warranty, no matter the age of the unit.

Thanks so much for posting the link to the note. I happened to be on the phone with Whirlpool when I found your post. Consequently, our fridge and freezer defrost thermostats which were being replaced at the time I was on the phone and on-line have been replaced out of my pocket -- but Whirlpool is sending another pair of parts -- at no cost -- just in case we have a problem. Since we had already purchased the parts and our service man was installing them, we are not able to convince Whirlpool to cover that. However, a spare pair of defrost timers may come in handy.

For those who are wondering where the defrost timers are hidden -- in the back right hand corner at the bottom of the units (when you're looking at the unit from the front). The electrical diagram can be found on the back of the units -- but they don't show you locations of parts -- just what connects to what -- sort of like a subway map.

Again -- thanks for your help!