First thing I would do is get a syringe. You can buy one from KTM, but I use a big ole cow type from the feedstore(or AutoZone). Connect about a foot of poly tubing to the end of it(6mm or 1/4" OD). I would drain/pump the stock oil compeltely out from the bottom. Once it's drained, use your syringe to fill the line and reservoir with type F ATF from the bleeder screw . Filling it and pumping the lever won't cut it on these, you need the syringe for sure. Use the rest of that type F ATF to fill your gearbox. Those clutches seem to be nightmares for aftermarket buyers, but on the OEM KTM's they seem to be very reliable.