Case 550G dozer won't move, update and questions

This is the dozer I posted about several weeks ago. Pulled it out of mud and have not gotten tracks to turn since. Before it dried up enough I could get to it to load it, it rained over 8". Water was up to about the alternator on engine for a couple of days. Drained water and oil out of engine and started it, runs fine. Got it home and drained everything else and replaced fluids. Trans pump was not working so replaced torque converter, pump, all seals, cleaned everything front to back and put it back together. Have pressure on dash gauge now, but still won't move. Have questions.
Driveshaft turns when running, but stops when I put in forward or reverse. Motor sounds like it has some load on it but does not bog down or try to die. Is this normal? If I speed up motor dash gauge pressure goes far to right (orange) but if I mash brake (right or left) pressure drops back to green on gauge.
Tracks have a lot of dried mud still in them, do you think this could have them stuck and not turning?
I have not given machine a lot of throttle, pressure wants to run on high side of gauge at high idle and only goes down to green when you hold down foot brake, am I gonna blow something if I speed up motor?
Is not my dozer and I never ran it so cannot tell you what pressure on dash it ran before now.
Parts book shows it has parking brakes that are "spring applied" when stopped. Is that correct and could they not be releasing and how can I tell without tearing into the brakes?
Sorry for all the questions but am not that familiar with a Case (I own a Komatsu) Any thoughts would be appreciated. Thanks.

Check out the parts diagrams for a better understanding of where everything is if you haven't already.

That said, if the driveline isn't turning when a load is applied, it means something is wrong inside the TQ and the power from the engine isn't being transmitted through it. It sounds like you've had all of that out of the machine, and replaced/resealed it already. Even so if one of the seals on the pump, etc happened to get messed up when it was being reassembled, it's going to create problems. Too there is a pump relief valve (#6 in the parts pic) in the housing as well. If it wasn't taken out and cleaned up, it's very possible it's stuck open.

Without knowing the pressures on the system it's hard to exactly what's wrong, but the fact the driveline stops when a load is applied pretty much narrows the problem right now down to the converter oil system.

I wish I could be of more help, but without more real details it's hard to say much more. I hope this helps.

If you have any more issues, info, etc, post again, and I'll do what I can to help. Regardless, let us know what you find.
Poke here for parts

Thanks for the info, but after checking this out again today, I can get the tracks to move a little. I really think the parking brakes are not releasing for some reason. I do know power is getting through to trans and sprockets. Released track adjuster tension on tracks since they were very tight with dried mud in track chain. Did not seem to make any difference in how well track turned. I am gonna think this out a little more, but I really think I'm gonna have to get in the brakes to find the problem.

I'm still thinking brake/brake control problem.
Gauge moving when brake is applied says it is getting
(some) control input.
The brakes are tied to the trans controls- engage & disengage-
you can get some idea of how they work by looking the parts book over,
but I think you really need a service manual and run some tests.
You might get a gauge on the brake release line and see what you have,
but w/o service specs would be kind of guessing.
The motor load but not bog, same thing, it's a guess without actually being there
or running a TC stall test, but is somewhat normal.
The driveshaft not turning is normal-out of gear it will spin, in it wont
until machine moves. Think of it like a car/truck w/automatic trans,
in drive brake on shaft still, brake off shaft turns, truck moves.
With when & how this happened, affecting both sides, I'd look at brake/safety
controls, esp wires & switches.
Sorry I don't have a G manual, only D, and their brake & controls are
different so I can't look up testing.

Thanks CJinMI. I do have a parts book and have looked at brakes. Told owner I would go no farther unless he was willing to get a service manual. Supposed to be here next week, I will check all safety shutdown devices before I would even think of taking it apart. Hope service manual will point me in the right direction. Understand now about the driveshaft turning. Thought that was correct, just wanted to be sure. After I saw tracks actually move a little a few times, I know power is getting to sprockets. Something is just not letting them spin free. I really don't want this job, but is a friend so I have to help. In hindsight, I just wish he would have stayed out of the swamp. Thanks.

There is a park brake valve located on top of the transmission - next to the batteries.
1) Check for voltage req to release brakes.
If no voltage check neutral start switch - lever raised to allow control lever operation.
If power is present - check coil / solenoid operation - If coil is faulty, an entire new valve is required P/N 1997074C1
2) If power is present & coil is operational - check charge pressure.

I think your problem is electrical.

Cheers from Australia ;-)

Thanks alrman for your reply. Didn't know you had Case in Australia, but I guess all the big name companies are worldwide these days (never been to Australia, to far from home for me!) I thought I had checked that valve and microswitch you are referring to but that was back at "the swamp" so maybe I missed something. Will check it again. Thanks for the help.