Dirty "Y" Rails???

[SAA3840]

I just fought a battle trying to find out why I kept getting "Z" truck stalls. That was fixed by gluing a small sheet metal tab on the board tracking lever. Got through two 2hr+ carves just fine.
I started another carve, which is attached, and about 2 min into the carve, the machine starts telling me to "Clean the Y rails". Well, I cleaned them, then wiped them down with dry silicone lube, checked the bearings, which all four on the "Y" truck turn freely. I started the carve again and got the same error message plus the machine cut all the way to the edge of the board. The carve is a sign that says "Benchrest" for my gun club. The word "Benchrest" is in a .250" deep carve area. The machine carved the left edge of the carve area, which has 1/2" feathering and then ran all the way to the edge of the board on the keyboard (Top) side. The same carve did exactly the same thing twice. Luckily I don't have two pieces of expensive firewood as I was carving on a piece of 2 x 12 DF. I am running 1.186.10507 firmware,
When I was chasing down my previous problem, I cleaned out the "Z" truck rotating disc, there's nothing in it to cause problems. I took the "Y" truck off of the "Y" rails and checked the bearings, they all turn freely.
There are 314hrs on the cut motor, the brushes have been replaced twice, the most recent time was a day or two ago. And both my previous projects were done using the newest brushes.
It's a "B" machine, serial number starts with B.
Any ideas what my problem is??

[unitedcases]

Y cog bearings? Dull bit? Thats about all I can think off.

[fwharris]

Check to see if you have any play/movement in the Y gear box and gear. With that many hours it might be time for new bearings in the gear box.

[SAA3840]

I might have agreed with you about the "Y" gears, but I think I replaced them not too long ago. I could be wrong, I've been wrong before...

[SAA3840]

Dull bit is a possibility. But I'm not ready to sacrifice another piece of wood to find out.

[aokweld101]

I had the same thing happen to me last week and I had a piece of wood stuck in there somewhere I turned the machine off and made sure the x & y gears moved freely by hand.. I had a hang up.see if your x & y move freely If they don't then you have something stuck in the gears.

[SAA3840]

The "Y" and "Z" trucks both move freely (when the machine is turned off).
I guess what I'll have to do is take the top off again and take a look at the "Y" bearings and gears as well as checking the "Y" belt adjustment. I can't think of anything else. Well, I guess I could check the "Y" motor's clear disc too.

[blhutchens]

When you upload the mpc to the flash card on the settings use optimal and it will slow the feed rate down. My guess is it is a hard wood and doesn't have time to cut, thus causing a y stall. Just ran into this on acrylic. changed from "best" to "optimal" and she carving like a champ

[SAA3840]

The wood I've been trying to carve is douglas fir, (a common 2 x 12) which isn't very hard. What I did find though the "Y" motor rotating disk cover had a bunch of sawdust in it. Cleaned that out and put everything back together. I haven't had a chance to run it yet, but I'm pretty sure that was my problem.
While I had the "Y" motor out, I re-lubed the gears and checked the bearings, as best I could, there's no play in anything that I could see.

[SAA3840]

OK, my machine performed beautifully today. I completed the carve that gave me the "Clean Y rails" error. The problem apparently was the plastic cover on the back of the "Y" motor. After I cleaned it out, the carve ran just fine. So the next time I get a "Clean Y rails" error, I'll check the back of the "Y" motor for sawdust.
Thanks to all that offered solutions.