Hey, I need to get my framing nailer working again asap. It is a Dewalt D51844. I am not entirely sure how the driving piston is supposed to return, however, it fires but wont return without being pushed back up. I've oiled the piston shaft and checked the o rings on the piston head and in the trigger assembly. Occasionally after firing it it will blow off air from the tip and slowly return back up with a comically long delay. The gun also started firing nails out uncontrollably upon connecting it to the compressor once and only once... Any diagnosis or ideas? Running it at ~110psi with 22 degree plastic collated nails. This issue arose after driving at least 1000 nails without a problem.