If anyone has experience with surface grinders, and may have an opinion on the cause of this problem i would appreciate the help.

So i was skimming some parts on the surface grinder and had been using it for an hour or more, when the head moved down on it's own, for no apparent reason.
So the machine is automatic, but the vertical is manual.so what made the vertical adjust on its own?
It did it several times, lowered the head and ground into the finished part. requiring me to do a lot more work to remove the deep pass.
It seemed to do this completely randomly.
I would do dozens of passes with no problem, and turn the handwheel each pass to lower the head, then out of the blue, it would lower all by itself.
I don't know how far it would go, as i would quickly turn the handwheel to raise the head as soon as it started.
It would go deep enough to see the sparks increase, hear the difference , and see the ruined surface.
So the machine has a hydraulic left to right travel, an electric front to back step over. and an electric rapid vertical, and a manual vertical for cut depth.
I am going to take it apart to see whats going on, maybe something has come loose. The machine is not an ancient worn out machine by any stretch.

When i started to take it apart i have found another issue; the guides system for the head vertical travel is eight bearings and two machined tracks; four bearings on the inside and four on the outside.
I noticed that only three of the bearings on the outside were in contact with the tracks. The bearings are cam bearings, so they can be adjusted 0.010" but one of them even at its max is still a few thou shy of touching.
One of the problems is i can't get access to adjust the inside ones without removing the entire head and tracks. Plus there is going to be a lot of work to align and verify the head if i have to go messing with the bearings.
So i may have to take the head off. I could just make a new plug for the one bearing and bore and grind the hole further off center so that i can adjust it to touch without adjusting anything else, but i guess i will have to check the head alignment first to find out which way to proceed.

Anyone with experience that can offer some advice would be appreciated.

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