G’day team, I’ve had this issue for a couple of days now, I’m doing a number of plates each one running large print times with short periods between PLA filament changes (lots of fine details) Slot 1 has a recurring issue - but only occasionally, where it will fail to load the filament to the extruder (as the error display shows in handy). The weird thing, is that each time I can select retry from the handy and it will then load the filament without any issue and continue printing until the next time it occurs. This has happened approx 6 times in a 10hr period of probably 100 tool changes in only that filament 1 slot.
As it’s intermittent, it makes it difficult to diagnose and also, as handy doesn’t send me error notifications, it’s usually been sitting a while before I’ve noticed and have been able to clear the error.
My first thought is that sometimes the filament is being drawn in too far and it’s going past the feeder for it to be grabbed the next time it’s required but then I don’t understand how it’s able to then grab it when I select resume after the error?
Does the feeder mechanism have a movement it does when it encounters a feeding issue to try and self-rectify? Cheers
Maybe you have a slow clearing sensor inside the AMS. By the time you get to retry it has cleared with no trace of problem or it happens just fast enough to halt printing but not throw an error code. 
Thanks for the replies so far, my print has now finally finished, so I’ll be able to have a good look when I get home and see if anything is misaligned or loose. I did notice that spool is a little noisy compared to the others, perhaps the rollers are tighter. I am using the Hydra spool holder trays with tapered rear rollers to keep the spools central.
Bought the A1 Combo, AMS lite constantly is having issues loading filament. When i hit retry it works but nearly fails every other filament change. Created support ticket week ago still no help. They on vacation?
Hi Djgrafitty99,
Any news on this problem? I received a new A1 combo yesterday and have problems ride away with feeding from unit 2. I checked the nozzle but there was no clog. The behavior is that the ams lite does 3 attempts to feed it into the nozzle when the filament sits near the nozzle.
I purchased a P1S early December, i had quite a few issues with this problem, Support where pretty quick to respond and offer some solutions. They suggested i downloaded some files to print to connect to the AMS and tubes but i am reluctant to use this as a fix, i see it as a band aid really, and this should be fixed without and modifications. I love the printer, the “failed to pull back filament” is random for me, it was happening on every print, but the last few days it’s been fine, which is odd. I’m hoping the next firmware update will be a solution.
I`ve the same issue with my A1 combo. Support sent me a new Extruder kit but it was not the root cause. The filament always get stuck in the filament head. It passes the filament hub easily.
I was able to solve this problem for my P1S. The problem was that the ptfe tube was not completely seated in the extruder. I was able to push it in just a little more and did not have the problem since.