Hitachi 3D2 tape mechanism

Hi there,
I am currently working on a Hitachi 3D2. After doing some service (cleaning, painting the red ring, new woofer chassis, new piezo tweeters it performs better than expected.
I have a question regarding the tape mechanism. All functions work OK, however I had a scratching noise coming from a small “piston” which is pushed against the flywheel by a small spring.
I pushed it back a little bit – now it does not touch the flywheel and the noise is gone. The white plastic part (which holds the piston) is related to the pause-function and moves 1 millimeter once you press or release the pause button.
Does anybody know the idea behind this piston? Pause and so on still works, but it seems that this part of the mechanism is still not in the 100% correct position (?).
Best regards
Helmar

This Hitachi have standard cassette deck.
This white plastic part (which holds the piston) usually is so close to flywheel. This is her position.
I guess she's got off, because it is under tension from the spring.
You have to press it tight, so that it does not go out.
If this happens, the pause may not work.