Belt slipping on bottom of washer-pulley shims on pump slipped out

After taking the motor off (it looked loose to me!) and stripping out the bolts on it, then finding that the bolts holding the motor were permanently affixed to the motor (and they were an odd size not available at the hardware store), I drilled the bolts out and put in new ones (on the motor) and re-affixed the same. I still had a problem. I then went online and found that most people had problems with the water pump. I looked at the pulley on the water pump and found that the inner shims had slipped out on a permanent part (and could not be put back in with the basic tools I had on hand). I ordered the pump online, and replaced the same. Took about 30 minutes after I found the real problem and got the parts in. My pump had a permanent metal disc on the bottom which did not come with the new pump, but the new pump fit without it. Machine works fine now.