Signet TK7SU - new stylus?

I could use some advice on what to do if anything with my Signet TK7SU cartridge. I would like to mount it either on my MMF-5 table, or on my soon to be delivered Pink Triangle with Audioquest Arm.

I purchased this cartridge new in the late '70s or early '80s. It was mounted on a Yamaha table with an S-arm and since it was my only source through much of the 80's I'm guessing it has well over 2000 hours on it.

I've always taken extreme care cleaning LP's and stylus, and looking at it under microscope the shibata shows no where at all. I've read through the stylus life discussions here which would indicate it needs a replacement stylus, and from what I can tell, good tip condition isn't the only issue I need to be concerned with - it's the the suspension that wears out.

My questions:
- Do I really need to replace the stylus - how does one know it's time?
- This unit came with the Shibata stylus, and I've not been able to locate a source for a true replacement (tried Google, KAB, Needle Doctor). Any suggestions?
- KAB recommended an Eliptical stylus replacement - and showed me an Audio Technica branded unit he believes is compatible for $37, and also a source for a Signet branded unit that costs $115. Is it worth going to the eliptical tip if I can't locate a Shibata?, and if so should I take my chances with the AT unit to save $80?

My alternatives are to spend my money on a new cartridge for ??$$, or upgrading the Goldring 1012gx to either the 1022 ($160) or 1042 ($180) and mounting it on the Pink. I also have an Ortofon OM30 that I'm currently running on the MMF-5

thanks in advance!!