TV Tuner's Channel 3 Gone Bad

[Jon1967us]

I'm currently dealing with an issue where channel 3 can't be fine tuned, but channel 4 can.

This tuner is on a CTC-16.

The mechanical action seems to be performing ok - gears engaged and turning.
There is a white plastic nub that protrudes out the other side of the wafer on ch4 that isn't there on ch3. I'm guessing that maybe this prevents from grounding by a tab that is spring loaded against the fine tuning wafer and defeating the fine tuning?

Anyone familiar with the CTC tuner?

Ch3
https://ibb.co/KFdjJfM

Ch4
https://ibb.co/DbvkV1d