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New problem: The Max v2 is losing its USB connection to the PC, which stops the print job in-progress. The hot end doesn't move from its last position and I get a glob of melted filament at that point - so saving the print and restarting from that point won't work. This has happened the last two print tries, each of which I discovered after the printer had stopped for some unknown length of time - I started the print job, waited to make sure things looked OK for the first few layers, then went on to other chores. I checked back every 10 minutes or so and that's why I'm not certain how long the print jobs had been stuck. Each of the print jobs had been running for at least an hour or so.

When I originally calibrated the Max, I used the iMac in my home office, and printed the fan shrouds without much trouble. Since then, I've moved the Max out to the garage and now run it from a Windows 7 PC - but I haven't been able to complete a print job yet thanks to this comm issue.

Is it possible this is a problem with the PC? The computer eventually went into sleep mode during each print job, but the printer seemed to be OK anyhow. Should I turn off the sleep mode on the PC?

Or is this a power surge issue? I'm running both the printer and the PC through a surge protector, but I can't imagine a power variance that would be big enough to cause a loss of the USB connection between the devices. We do not typically have issues with power surges or brownouts in our neighborhood.

Thanks in advance for any suggestions...

Problem is the PC going to sleep. Turn off the standby/sleep function. Printer was OK until its memory buffer ran out of commands to move/extrude, so it sat there waiting for more instructions... Meanwhile, hot end is oozing the glob you found.

The PC going to sleep is indeed the problem. I had that happen once, not fun.

Why not print from the SD card? That will eliminate the issue.

I now print from SD card exclusively. The USB cable is only plugged in when I am playing with the firmware. Leaving the cable plugged in while printing from SD card is also trouble waiting to happen. Launching a program that attempts to connect to the printer causes the printer to reboot, aborting the print.

Main reason I'm still using a PC - it's our "old" one that no one in the house uses anymore, so it gets to be our "3D Printer Server." One of my colleagues at the office recommended going the SD card route also.

BTW, turning off the sleep mode did the trick. Prints go on for hours... and hours... without problems. Well, without the same problem. Now I gotta work on print bed adhesion, but that's another topic...