This repair was performed on a Whirlpool Cabrio clothes washer Model # WTW5640XW0 which has the digital electronic controls rather than the older style timer, electro/mechanical controls. This washer was made in 2010. Simply having the diagnostic programs on this machine is wonderful and they work remarkably well and led me to the shifter/rpm sensor component straight away. It was a simple replacement by tipping the washer onto its front and accessing through the bottom. The machine was put back into service having passed all diagnostics and re-calibration. It worked for about a month. I had noticed on the removed part that the translucent window on the rpm sensor had gotten dirty and I cleaned it up thinking that was perhaps the only problem. I saved the part in case it might be needed in the future and was functional with the cleaning. On the subsequent failure, diagnostics led me to the same part and I discovered that the rpm window was as dirty as the part that I had replaced when it was removed and it was only a month old rather than 7 years old. I suspected a bad stationary tub seal was allowing some leakage into the transmission and the spinning parts were distributing it all over the inside of the transmission where the sensor is, and it was just enough that it would seep, get thrown all over, and dry. The scum on the rpm sensor lens was a dried brown crust and hard to remove. Therefore, I resolved to completely disassemble the washer, replace the seal, and refurbish anything in need. I found the spin basket, agitator, concentric drive shafts, and hub parts badly corroded and practically welded together. I thought it was never going to come apart and I'd have to replace the spin basket and transmission, so we went shopping for a new washer. However, with much pounding with larger hammers and liberal amounts of penetrating oil, everything separated. The only parts needed were the seal and the three hub parts that secure the basket and agitator to the transmission shafts. All back together, the first diagnostic pass failed at the spin cycle AGAIN! Time to resurrect the older shifter/rpm sensor module and VOILA! Success! The newer shifter/rpm module had in fact failed beyond the suspected lens cleanings, but the older one was still viable.
It is not often that a DIYer like myself gets totally familiar with an appliance that fails and I always wonder if the effort is worth expending. But, for the adventuresome...duty calls.