Paul's comment is on the money. I have had a VPI HW-19 Mk4 for many years, and my older home has rather "flexible" wooden floors. Like you, the tonearm on my VPI TT bounced whenever there were footfalls near its' location (it even bounced if our overweight cat jumped down from the couch to the floor). I tried a lot of different approaches to solving the problem, and none were totally effective.Then, about 2 months ago, I replaced the TT's spring suspension with the Sorbothane pucks from VPI, and I no longer have a problem with tonearm "bounce". (An added, unexpected "plus" is that bass frequencies seem tighter.)
The pucks (and the Scout / Scoutmaster cone feet) can be purchased from Elusive Disk. Here's the link:
Installation of the pucks requires some minor changes to the turntable. Rather than go into all the details here, please drop me a personal E-mail and I'll tell you what to do.
One other comment: if you decide to buy the Scout-type cone feet, note that it is less expensive to buy them separately from the pucks, rather than buying the upgrade package which includes both items.