Cartridge Tacking Problems - Help please


I have major tonearm/cartridge tracking problems that seems to have gotten worse, leading me to believe there's a problem with the arm. Can anyone suggest what I can/should try to further diagnose the problem?

Here's what it's doing:
On some (becoming many) discs, the cartridge will just skip out of the track, as though there's a scratch, or someone bumped the stand. Changing the anti-skate setting (ie over driving the anti-skate to 2.5) helps a little, but doesn't cure it.

Here's the set-up:
Pink Triangle original table
Audioquest PT6 arm
Signet TK7SU cartridge with new stylus
(the the problem exists also with the old one)
I have no damping fluid in the trough at present

Here's what I've done:
Table is leveled and set up properly
Arm/Cartridge is set up and aligned (and quadruple-checked)
Tracking force is set at 1.75 g, which is the max recommended by Signet. I've always tracked this cartridge at 1.25 g on my old table and it worked beautifully.

thanks in advance!
bdgregory
This may be a little obvious but it did happen to me. Om an Sme 309 ,which is "fatter" at the pivot end, I lowered the arm to adjust VTA. It skipped/jumped on some discs because they had slight warps and the warp hit the arm as it neared the end of a disc!Duh!
I've never seen acompliance mis match so sever it cause the cartidge to skip, mistrack yes but not skip.
If it's not the above I would have to concour with other poters that it is a mechanical bind of some sort. Hope this helps
thanks everyone . . . there are a number of suggestions I need to followup on here. I'll be out of town this week so they's need to wait til next weekend.

I have given thought to a new arm, not sure if the RB300 is my first choice or not. There are a few things that appeal to me about the PT6, so I want to try and make it work.

thanks again, I'll post results after the next tear down.
Your cartridge is 25+ years old. Sounds like it might be time for a new cartridge! The suspension elements of a phono cartridge will not last forever, as the rubber suspension parts will decay. This can occur even if the cartridge has not been used very heavily.

Also, do you have a sturdy table stand, and have you changed the TT stand recently?
thanks Fatparrot . . . interesting point, on which I'm a little ignorant, but I thought the suspension is in the stylus assemble (which is brand new). At least as I look at mine, the only moving parts are in the stylus asm. Am I way off on this?

In any event the new cartridge is on the way and will be tried out this weekend and tell me the answer.

I do have a sturdy table stand, so I think I've ruled that out.

thanks again.
Update - the problem is solved. It turns out that the horizontal bearing was binding up, and I'm pretty sure it was from damping fluid contamination. I mounted up my new cartridge this morning and the problem had become worse than ever. It wouldn't track at all, so it seems the silicon was becoming more caked on as time went by.

I cleaned the silicon residue out of the bearing cavity as well as I could with paper towel, and then sprayed the bearing with Deoxit to de-gunk and lube the bearing. Before this procedure the binding was noticeable (ie I could feel it in my hand as I moved the arm). Now, it's tracking fine, and sounds lovely. The Grado Sonata is great, and it seems now I can sit back and listen to music on this table rather than constantly tweaking it.

Thanks to everyone!!