Are the upper and lower grooves of the feed rolls aligned properly once clamped in place without the gun connected to the feeder??? This most definitely needs to be checked first before even reconnecting the gun back on to the wire feeder because even a slight misalignment can cause shavings to be produced and dragged into the conduit - hence, the condition you describe...

Btw, what type of Aluminum drive rolls are you using??? I ask this because as you know, 5356 Aluminum is not a soft wire and you may or not be using the appropriate drive rolls for the type of wire being used. ;

Finally, out of the hour you mentioned that you use the gun... How many minutes of the hour are you actually welding, and at how many amps & voltage? And what is the duty cycle rating of this model?;)

On a separate note; I always preferred the MK model wire feeders mated to the MK Python push-pull guns to use instead for welding thick Aluminum. ;)
However, please make sure that the correct drive rolls as well as the groove alignments between each of the rolls on the wire feeder are also appropriate according to the equipment recommendations and the harder type of Aluminum wire being used. ;) Hope this helps! ;)

Respectfully,
Henry