I tried several types/makes of footers on my WTA such as Mapleshade heavy brass cones, Mapleshade Isoblocks, Vibrapods, and Stillpoints. None sounded as good to me as the stock squash balls.
I also tried a couple of platter mats including a Millennium M-LP. Again, the stock mat was the winner.
I am using a non-stock PS for the motor. My WTA was delivered with 2 different "wall wart" PS, one of which hummed a bit all of the time and one which hummed occasionally. I looked though a box I have of several DC PS and chose a well made 1000mA 12DC PS that is not of the wall wart type. It has a 3 ft. power cord leading to the PS and then the lead to the WTA. The PS itself is situated on a Mapleshade Isoblock with a large Mapleshade brass cone situated on top (flat side down). Not only do I have no mechanical hum, but I'd swear that the sound seems to have more "drive."
Think I'm done with the tweaking ---- well, for a while at least ..
I'm using the WTA with a London Decca Super Gold cartridge - the "livest" sounding phono cartridge I've ever encountered. I bought the WTA specifically to use with this cart since it puts a substantial amount of energy into the tonearm. The WTA arm damps the resonances wonderfully and lets it sing. It is a near perfect match.