washer problems.

Help please. I have a maytag washer model no. MAH8700AWW serial no. 10587907GJ. The washer doesn’t drain all the way, there will be a little bite of standing water when its done washing the clothes. It also walks all over the place when in spin cycle. The water pump in the back of the washer has one bolt missing and the other two have striped threads. I purchased this from a guy on craigslist and think i got screwed. Not sure ware to go from here, I don’t have any manuals either.