Tool Clamp Fault 134?

1995 HAAS VMC VF-OE having repeating problem, Tool Clamp Fault - 134
134 on tool change 2 - 3 almost always. Clear alarm, do recovery and works fine until repeat program, then 134 again. It even does it without a tool in the spindle. The program uses 4 tools and repeats the 2 - 3 tool change okay the second time. Run the program again and tool clamp fault on the 2 - 3 tool change. Once in a while the tool change is fine but usually tool clamp fault.
Out of 84 parts it occurred more than 50% of the time (way more).

It is difficult to explain, because you can't see the parts until the front cover is off, but I will try. Okay I found a picture to help.

When the tool release piston moves to clamp the tool, after a change, it has to force the air out of the opposite side to do it. But, there is a filter on the sonenoid where the air is discharged and that sometimes gets clogged up over time. Therefore the air can't get out fast enough and hit the tool locked switch before it times out. You get the alarm, but as soon as you clear it you are okay because by then the air has escaped.

See the picture and trace down the lines. You will have to remove the cover, but then you will see the piston try to move all the way up and not make it in time. Don't change the switch location, clean the sintered brass air defuser.

If I had to bet, I would say that this is what is causing your issue.

Good Luck-----Mike