Stock z tramming

Just a heads up to any that are having issues tramming the spindle mount.
Are your z axis eccentrics constantly coming loose?
Loosing steps on plunge but don’t know why?
Z belt stretching or working loose?

Check for parallel between the v-extrusions that the z rides up and down on.
I was working on doing a maintenance check and removed the spindle, and then the z plate that the spindle mount attaches too. I was checking the v-wheel fit to the extrusions when I noticed the v-rails were not parallel to each other.
Grabbed up a caliper and consistently measured the gap at the bottom at 3.018 and at the top was 3.0245 / = pinching at the bottom.
I used 2 x 1-2-3 blocks to parallel. Loosen the screws that hold the extrusions. Set one block at the bottom and clamp the rails to it, then set one block at the top and clamp. Tighten the screws and re-measure.
Mine are now at 3.001 at the bottom and 3.0005 at the top. The z-movement is now very smooth and the spindle tram checks to better than I can see (sober and with a magnifying glass).
On milling a flat face on stock with a #201 bit there is no measurable ridge/scallop left. You can “see” the milling mark but you can not feel it. When I run a dial indicator across this I do not read a variation.