Backhoe Thumb Control Help

I have a 1988 Dynahoe 490 with a thumb. When I looked at the machine the thumb was not hooked up but he fellow that I bought from said that it worked fine. He said that all you have to do is push down on the foot pedal on the RH side of the floor and use the bucket curl lever to to open and close the thumb. The bucket curl works just fine but I can't get the thumb to budge. The thumb has it's own hydraulic cylinder and 2 lines go up to a pin between the boom and dipper stick. There are to other hoses that go to the bucket cylinder for curling control. There is a small hose that goes from the pin to the foot control in the cab. When I push down on the foot control the small line seems to move slightly as it's being pressurized but nothing happens. The bucket curls whether i push on the foot pedal or not. There is a small reservoir container on the foot valve that is full of oil. I pumped the foot pedal several times and nothing changed, same problem. So, "I think" that the the foot pedal, might be ok because the line seemed to be pressurized to the pin. The lines connected to the pin between the boom and dipper stick are not leaking and if the thumb lines were crossed the cylinder would work in reverse, and that would be an easy fix to swap lines. So, I think that my problem is with the hydraulic pin between the boom and dipper stick. The fellow that I bought the machine from has no clue of who made the thumb. His father bought the machine used when it was 2 years old and it had the thunb on it. He's used it and it always worked, doesn't know what my problem is. I've tried looking on line to find something like this set up and they all appear to be set up with foot control valves going directly to the thumb. Very expensive set up even for the foot valve. I was hoping to find a new pin that I could just swap out. I can't find any Dynahoe option so that's a dead end. Does anyone out here have any info on who made this set up or know of a place for replacement pin? I have a lot of work where a thumb would be very helpful. Any help would be greatly appreciated! Thanks!

Some pictures might help. Sight unseen, my guess is it is aftermarket, not a Dynahoe part, and what you are calling a pin is part of a hydraulic diverter valve actuated by fluid from the foot pedal. The internals of the valve may stuck from setting. Someone might recognize it if you post pictures of the valve (pin) and the thumb.

This post was edited by Jim.ME on 07/23/2022 at 04:58 pm.

I agree, you may have to persuade that
pin to get it to move. Pictures would
definitely help.

Sorry for the late reply, got pulled away for help on another problem. Yes, upon further review, the input that I got was erroneous! It definitely is aftermarket as the parts manual does not show anything but straight hydraulic hose between the control valve and the bucket curl cylinder. There are some diverter valves up on the boom behind an access plate. that my son found. Just need to get the plate off to see what there is there and how all this works. I tried looking for a hydraulically operated diverter valve and couldn't find anything. I wonder if there might be a small spring loaded hydraulic cylinder that opens the diverter valve when the foot pedal is moved and the spring pushes it back when the foot pedal is released. Just a wild guess and won't know until we get that panel off. Got the bolts soaking with PB Blaster hoping that they don't break off. As soon as he gets it off he can take some pictures and I'll send them along. Thanks!

I couldn't agree more, working on that. I sent a reply back to Jim ME about that. Waiting to get some time to work on the old girl. She's waiting patiently for some time and attention!