serial number C10037 There is a block on top of the swing motor that’s leaking, pulled it apart and one of the o rings was fubar. The parts book doesn’t give part numbers. Only way to get the 3 O rings is by means of a service kit for 1100 bucks. None of the o rings in my komatsu kit seem to match up. Wondering if someone can help me find proper o ring numbers, don’t want to guess here. I’ll try and attach some photos from my phone.
If you have a hydrostatic pump repair shop close by or that you can get in touch with, I would check with them to see if they can help you out. I say a hydrostatic pump repair shop because a lot of hydraulic pump repair shops don't mess with piston pumps and motors.
Try a JIS - 90 durometer kit