I have an old Marlin model 783 22mag that I dearly love even though I know it isn't an expensive gun or anything special, but it shoots "lights out" and I really like 22mags. Anyway, it has gotten to where it wont always extract the spent shell when I cycle the bolt sometimes and I have to very firmly close the bolt with a little force in order to get it to grab the shell. What might be the cause of this and would it be an easy fix? Thanks!