Hello: I have a bottom freezer Amana model BM20TBW fridge with a frost problem in the freezer. Frost is building up near the front of the icemaker in the corner. Sometimes, maybe once a week, there is a very small puddle of water at the bottom of the freezer door. I assume defrost cycle is not working? Can you troubleshoot this with a DMM (continuity of switch, motor, etc)? Also, where is the defrost motor? Thanks for any help, Bill