Tone arm bounces

Sounds like acoustic feedback to me..Coming from the floors all the way back to your turntable amd arm...

This sounds like a problem related to the cartridge choice and arm compatability. I would check the effective mass of the arm as well as the cartridge then look up the calculator online that determines the resonant frequency. From what you are describing the resonant frequency is too high and not within acceptable inaudible frequencies below 15 Hz where the human ear can't recognize them. You interpret it as a bouncing arm but really the cartridge you chose isn't compatible with the arm on your turntable. Although I could be wrong.

What I left out was that at high volume compatability issues really become obvious. At low to normal volume it may not be audible so you assume because it sounds good to you that all is well. The other thing you forgot to mention was the dynamic compliance of your cartridge, is it, low, medium or high? Why did you choose that cartridge, was there a particular reason, was it recommended to you??? With a little more info we can figure it out. Send me an e-mail if you're interested and still want to cure your turntable of this problem.

Try sending someone an e-mail with the new format---doesn't work like it used to.