yep i would of checked that inching valve too
just replaced one like this recently
an eazy job to do :o)

Thanks Guys. I got it replaced and it works great!

Kevin is correct, if no visable leaks, the inch valve is more than likely sending the oil into the trany, not good for the seals/O rings, tends to swell them. Some guys rebuild the inch valves, sometimes w/ no success, other guys buy new valves if available, other guys just block off the fluid to the valve.

Is probably passing thru the inching vavle on the left side of the transmission and being pumped into the transmissin itself,on the left side under the floor board is the inching master cylinder(the brake master cylinder is on the right side)....if you follow the brake line coming out of the inching master cylinder it goes to a valve on the left side of the transmission this valve has a cup in it much like a brake master cylinder or wheel cylinder if this cup is bad then your fluid will be going into the transmission

C500 is not a complete model number - but rather a a design style that covered trucks from 3000 lb up to 15,000 lb & maybe larger lifts starting in 1969. You need to supply a complete model number (eg C500-50 (5k cushion or C500 Y -080 8k pneumatic tire) and serial number - ususaly found on a a metal (aluminum) plate pop riveted on the forklift close to the operator seat - some times on the front side cowling (aka dasboard). If this plate is missing the serial number will be stamped frame in the following format XXXX-XXXX-XXXXX - the actual number of digits may vary & there maybe letters in the first & third numbers. On older machines these numbers may have been painted over several times - start scrapping). The complete s/n is the most important bit of information.