my 52 is fairly new and sometimes when i try to cock it the cocking arm gets kind of stuck and it wont cock and it feels sometimes like something is catching on something inside please help
there are several fixes that involve disassembly and de-burring and polishing of parts.
1. the piston stem has a hard edge on the end of the mushroom like end that enters the trigger group on cocking. it catches on the latch plates. the hard endge needs to be rounded slightly and polised.
2. the latch plates need to have thier holes de-bured on the side that faces the barrel. the back side is beveled and should not be altered. these plates need to be de-burred and polished and lubed with moly where they rub against each other.
these two things should help a lot. in some of these guns the piston stem is loose in the piston and has quite a bit of movement and will not align properly with the trigger group. in that case a fix is to have a metal guide made that will be precise enough to hold the alignemnt.
if you do not have familiarity with the mechanics of the gun ahd are not comfortable doing this work then i strongly suggest that you have John from PA or Rob hawkins do the work for you.
There could be many different things causing your trouble with your gun. First off in my own expirience over the years if you can start doing your own repairs you can save money and time shipping your gun to be repaired. There have been many good posts and articles on the 48/52 type guns on the net in the last few years. If though in doubt and the gun is new you can always get a repair done by Umarex. If you can take the time to get familiar with the design of the gun and look at some articles you should be able to make some repairs at home. Very difficult to know what the problem exactly is that exists in your gun without an inspection.