I've done a little searching around and discovered comments here and there regarding the change in capacitance that can occur with heavier RCA cables, which is what the prior owner of my deck put on...I'm not certain what the brand is and I'm not near the deck right now to look, but they're very thick cables with shielded plugs, and the cable itself is probably 75% longer than a standard table cable would be.
I'm starting to wonder if this could be where my problem is coming from, since otherwise it would appear to be in the tonearm wire. I haven't checked the solder connections for the RCAs yet, but I'm wondering if I should just replace the fancy cables with plain old RCAs when I do to see if it makes any difference.
Is there a hard and fast rule about what cables are usable with turntables?