Knocking noise during agitation cycle - GE WNSR2100T8WW

I believe you must have one of the bottom of the line cheapo washers, as I do--the one with the plastic, rather than steel wash tub and basket? These are pretty poor machines. They cut corners drastically in every part of the design. I've replaced the aluminum hub that supports the spin basket ( the hub is bare aluminum and corrodes within about 5 years use from the highly alkaline detergent, then it fractures under mechanical stress. Then the motor burned out. I was able to get a nearly new motor on ebay for $90 incl. shipping. (BTW, if you need appliance parts try GOOD Appliance on ebay for new and salvaged parts--they're excellent! 100% feedback rating) However, I now have the same problem--a fairly loud knocking noise during the agitation phases of the cycle. This is cause by a really crappy transmission design that does not wear well. My advice is just ignore it as long as it works and isn't leaking oil and the tub seal is still good. If it does finally go to pieces get one on ebay--that is if you feel up to doing the job yourself since a repair person would charge more than it's worth to install it. I believe new ones can be had on ebay for about $80, some are sold with seal kits. Bottom line is--if you want a machine that will last you for 15-20 years--don't buy a cheapo model. The front loaders are better as they use far less hot water (energy and water savings) but a good one is going to be anywhere from about $800 to $1600.