Try to determine where the jam is occurring.
If you take the Pheed off the marker, will all the paintballs eject if you release the plunger? If not, then it is likely a feedplug issue; contact me and I will send you a set of differing feedplugs that should fix the problem.
This is most likely a misaligned feedport/breech interface. With the SpringPheed mounted to the stock class body, remove the marker internals and the feedplug, and check to make sure that the front of the lower feed port and the front of the breech line up. If they don't, you may need to sand the forward part of the lower feed port. Use sandpaper wrapped around a 5/8" dowel to open up that portion, and also sand the inside at a 45 degree angle to help feeding.
This could be due to two things - the mounting screw may be extending into the marker body. You can check this by removing the internals and looking into the body with the Pheed mounted/tightened. If it's too long, you can grind it down or get a shorter screw.
This may also be due to bad feedplug/mount geometry, and can be fixed by relieving the forward feedport lip and feedplug.
Disassemble the feed and check to see if there is any dust/debris interfering with the plunger. If not, then with the spring removed and the plunger/screw installed, check to make sure that the plunger drops freely if you release it while in the Pheed body. If the screw is hanging up on the screw slot, then you may need to turn down the screw in a drill and use files or a Dremel to grind it down. I can also send you a set of ground down screws.
This means that the locking slot is not long enough; you can relieve it using a small round file. You can also try turning down your plunger screw and putting a small piece of heat shrink tubing on the screw shaft to provide friction.
This is typically a Generation 1 problem, as the powdercoating changed the dimensions slightly and may cause feedport width issues. Try sanding down the inner lip and sides of the feed port using sandpaper wrapped around a 5/8" dowel. You can also relieve the curve of the feedplug to give the balls more room to drop free.