Rebuilt the vacuum pump from End-Y which failed a couple of weeks ago. Pump failed because one (or more) of the carbon vanes broke and the debris shattered the remaining vanes. With no air flow through the air chamber, for cooling, the pump overheated and thermal checked. This is a normal safety feature of these pumps. In the photo you can see the broken vanes in the bottom of the air chamber. After cleaning and repair the pump is ready for service. 

   At the same time, I also rehabed a second one of these "failed" pumps. There are now two functional backup vacuum pumps for the dust monitor system.