I have never had a car related glitch (Knock on wood). 100% of the time it has been motor related. Not enough break in, funky brush batches, dented up brush hoods/hung brushes.
The latest batch of 767's arc like crazy (like Putnams) if you don't break them in a ton (~300 sec). You amlost have to cut the com again after breaking them in, lol! I've been using E's and 99+'s lately because they are just as fast and you can just spool up the motor for a few seconds and they are good to go.