So I am going to answer your question by asking a few questions. The answer should be in there somewhere. You won’t have to remember 25 years ago. I can’t remember that far back either. Here are the questions;
1. Does the needle swing up to 3K (or about) and stop dead?
2. Does the needle swing up to 3K (or about) and float around that area?
3. Has the tach ever worked correctly? OOPPS, that was more than 25 years ago. Probably forgot!
A few comments. A needle that sticks at a given point does so because there is dirt in the movement. If inaccurate or the needle is sluggish, the tach electronics is defective.
In general, a stock tach will not work accurately with Pertroncx if it works at all. Some won’t work with a Pertronix. Seems like yours at least works a little bit.
The fix is to change the electronics in the tach. I can do this plus calibrate it so it is accurate at each RPM point. Tach is restored too. $175