So here are some updates.
I ordered a new driver from xylotex ($80 as a replacement board within the warranty period). Hooked it up, everything worked ... for about 10 minutes of cutting. Then one motor cut out.
One of my Y axis motors doesn't even lock up. After several emails with Jeff from Xylotex, it seems that it is again the driver. Coincidence?
Instead of answering my questions and helping me come up with a solution to the problem, I am just sent a new board, and am supposed to install it as is. Huh...
So after these emails, I have been notified that because I changed from rack and pinion to leadscrews, I have changed the way the system is "grounded", and because I have a dust collection system, I should have grounded each individual moving part before installing and testing the new driver board... Well this is good news to know after blowing up the second board....
This is not covered under the warranty policy because the failure was caused by "overvoltage" from static buildup. There's really no way to know what the real cause was, but as with most consumers, I'm inclined to blame the new piece that worked for 10 minutes instead of the machine that has had the same grounding, the same dust collection, the same level of static buildup, the same everything except the drive mechanism, which worked with a board for over 6 months and countless hours without causing any static buildup to cause a board failure. But... apparently, that's what the cause is and now I'm out the original price of the board, the replacement cost of the board, and the board itself.
Just in case - any of you who use dust collection... vacuum system... or heck, any type of cnc - be sure you ground every component and read VERY carefully before purchasing, installing, testing, using, or sending in your xylotex board.
Anyone currently using a xylotex board - don't change anything about your machine, don't even look at it differently - you may cause a lethal static buildup!