That's good!

Thinking more about it those pots may be for record current adjustments for VHS and S-VHS modes. Regardless, the circuit needs to be traced with an o'scope to find out where it's losing the chroma signal in Rec.

SVHS on standard VHS cassettes
 

I own two SVHS decks. Both JVC. (PAL multi-standard models).

I also own 30 or 40 SVHS cassettes. At its best SVHS is pretty impressive.

I found using the ET switch or drilling the SVHS hole in cassettes works fine ... naturally the best results are with the bestter quality VHS cassettes.

The most noticeable difference is in the noise level in the video, especially in slo mo or special playback modes.

Both vcrs are in perfect working order...and kept that way as they are pretty impossible to replace. I have progressively transferred any significant SVHS material to DVD simply for compatibility into the future.