Collision detect

Collision detect which axis?

How many hours are on the robot? Have regular PMs been done? Is the robot subjected to a lot of e stops? Is the payload set correctly?

Put your ear on the pulse coder and jog J2. If the gear is going bad you'll hear the grinding.

Dont know if this is solved or if it can be useful to somebody but have you checked your bg logic to make sure you dont have anything setting your col guard very sensitive ?

I have had some techs jogging robots and constantly crashing them to the point where the EOAT bends and throws off all positions (very sensitive EOAT design) so we set bg logic to increase col guard to 200 if robot is jogged in teach. That could be your case too

You can view your collision guard current setting in Menu->Setup->CollGuard. I would veiw what it actually is set at during a jog move. As mentioned above, it could be running BK logic that automatically sets it much more sensitive while in teach or have program logic that sets it less sensitive during the parts of the auto motion that would otherwise trigger the detection.