Nice deck and write-up, and good execution as well.
Spent a lot of hours running these 'back in the day'. A couple tricks I recall:
1. Close head gate gently. Flipping it up will impact alignment over a short time.
2. Spin up the idler before you hit play, if you're spotting SFX, etc. Many films have the "warbling telephone bell" sound effect because folks didn't do it.
3. You can quickly get reverse play by wrapping the tape under the capstan, thru the gap (backwards) and back over the top of the pinch roller. Poof, instant reverse. Use expendable tape the first time you try this, as it will reveal transport inadequacies quickly (!).
If you're still having capstan tracking issues -- have you checked capstan shaft for uniform diameter, top to bottom? Any slight taper due to wear could show up as mistracking, if your new pinch roller doesn't fix things. (May have missed progress on this in the write-up...)
Nice job!
Chip