I have a 1965 Clark C40MB, serial number C40MB-326-679-LPG. When I put the forklift in drive or reverse the RF wheel will spin, the LF wheel will not move. I have had the brake assembly on both sides apart to replace the leaking wheel cylinders. The brakes are turning freely on both sides, shoes are not sticking to drums. I have tested this with the brake lines disconnected from the wheel cylinders as well. Today the RF wheel would not move when in drive. What should I look at next? Where is the transmission dipstick located?