/// You didn't say if it now runs. I often patch a repair to stall until a better time to work on it. (My own) If the sock is bad you are pumping potential trash to the main pump, but!, you have been doing that already. I would spray WD40 on the area and test the ring. Stop is the ring is not solid and able to turn. Leave it there and start loking for a good used complete tank. You can repair, and coat the second tank with the polyester tank saver. I am not familiar with all tanks and the fit to your 85. Some one else will know. If your wrecker yard has a cross reference you can see which years are exactly the same.

Remember you would not have even looked for the bad ground if the system was working. You would still be driving with no concern or indication of trouble if it hadn't stopped. Coin toss your call.

I believe in fixing it all when I start. I have some hints if you decide to remove and reinstall the tank.