How to restart a print on a Makerbot

I have a Replicator 2X that keeps failing about 12-14 hours into a 16 hour print. It appears that the nozzle temporarily clogs, the feed wheel eats a half moon into the now-stationary filament and prevents it from feeding further, and I come back the next morning, to a printer proudly saying "Print complete!" with only 75% of my model done. A simple unload/load routine and the printer is good to go- no screwing with the nozzle, which I've taken apart before to clean an extremely impacted jam.

Is there any way to restart the print at a certain layer? Edit the file, perhaps? I'm very familiar with G code programming from CNC mills and lathes, so finding the restart layer would not be a hurdle if I could edit the file.

Beyond that, how can I protect myself against print failures such as this?

Unless you worked out how to manually place the code exactly at the coordinates you needed, accounting for the model being moved, shrinkage from cooling, etc.. there is no way to restart a print.

What you're dealing with is unfortunately common and you need to address the issue itself to prevent the jam from ever happening to begin with. The problem is that it could be a hundred different things.. from the nozzle impacting the model itself due to part warpage/peeling, a mechanical failure in the extruder (incorrect pressure/etc), or even a problem with the filament itself.

One of the early upgrades I did to my 2x (I had one of the first ones they built, not sure if they've changed) was to replace the extruders with an aluminum version somebody on a forum had built (devilsinthedetails.ca I believe).. ended up being a -lot- more consistent for me.

Assuming your extruder is the same as my original version, you may just need to adjust the tension in the spring levers.

Check your part for any warping or peeling of layers.. if it gets too high it can impact the nozzle and cause a jam very quickly.

Thanks for the input!

The machine has a cold pause, and that works just fine. I figured a restart at a specific layer height would be doable, since it already allows basically the same thing.

This is a later 2X with a decent extruder and lever design. Quality has been excellent, and there are no warped/separated layers on the prints that fail. Also, the exterior of the nozzle is clean after a failure, and I would expect it to have plastic mushroomed onto it if the reason for the jam was the print being forced against the nozzle.

I'll try tightening up the spring tension.