I'd recommend a complete disassembly. Preferably:
-Replace all the O-rings (O-ring kits can be inexpensively obtained through ANSGear.com or Ebay.com).
-Ensure you grease (Dow 33 equivalent) appropriately (see the manual, PBNation, and YouTube maintenance tutorials). This typically includes HPR/LPR O-rings and some of the internal O-rings.
-Ensure you oil (BreakFree equivalent) appropriately. This typically includes the rammer and bolt O-rings.
-Reset the board and LPR to stock settings (see manual).
-Finally, methodically reassemble it. Ensure you inspect every piece for wear, and ensure it is assembled correctly.
If the marker persists to malfunction, I would recommend contacting Planet Eclipse.