After adding my spoilboard, etc, it was time to level my gantry side to side, and also tram according to some new info learned in this post. Notes taken during process:
Tramming x rails front to rear and leveling side to side, part deux.
After running Z home, use zprobe and level, wires to two tubes and level as described at How do I tram the LowRider. Check under tubes with a piece of paper (or better, feeler gauges). If one tube is too high, lower it by tightening top two nuts and loosening bottom two nuts on z/x connector. Not much, just a small tweak. Zprobe again and check. Eventually both will be touching, then raise by 0.1mm and see if front and rear have the same friction. Zprobe one last time and note the Z setting. Move level to other side of tram and check again. If Z after probing is different, make adjustments to offset.
Z0 side, 136.46, Z far side, 136.72, diff = 0.2mm. Need to increase offset.
M666 to check current offsets, Dual Endstop Adjustment (mm): Y2:3.70 Z2:0.90
M666 Z1.1, then M500 to save. Running Z home and Z probe again. Z136.96 on far side. Wrong way??? Now check far side tramming. Y0 side high, tighten top screws and loosen bottom screws, probe again. Still high, repeat. Both touching, raise 0.1. Both feel the same when sliding paper between rail and level.
Home Z again, then probe, record Z setting after probe. Z = 136.620
Move level to Z0 side and probe. Z = 136.53. Increase Z offset another 0.1mm
M666 Z1.2 and M500. Home Z, probe Z0 side, Z = 136.46
Move level to far side, probe again, Z = 136.66. wtf, wrong way??
M666 Z1.0 and M500. Home Z, probe Z far side, Z = 136.49
Move level to Z0 side and probe. Z = 136.46
Check far side again, Z = 136.51 diff = 0.05mm. Done with Z tramming and side to side leveling