Parking brake self-engages

[Spudfarmer]

Howdy! I have a 1998 John Deere 770 compact tractor. I noticed the problem a few weeks after I purchased it used. The parking brakes would lock when I had not pushed the brakes in and engaged the parking brake. Only used to happen when I had stopped the tractor. Within the last few months, the parking brakes have locked up while I have been mowing. It brings everything to a quick halt. I mess with the parking brake lever and eventually, it unlocks. I have tried to find information on this problem but haven't had any luck. I did crawl under the tractor and checked to make sure all springs were on and all pedals, and linkage was free and lubed. Didn't seem to help.
So, I am trying to figure out what the problem is and how to fix it. I have not intentionally used the parking brake since I purchased the tractor. I think it might be safer without parking brakes than the situation I have now. Y'all got any ideas, answers, or whatever?
Thanks,
Spudfarmer

 

[bb770]

I have a 770. The parking brake is a bar with teeth that hits a tang on the left brake pedal, it locks the pedal down when you pull the lever up and push the pedal down. If your brakes are locking up without the pedals going down, I think you might have a broken return spring in one of the brake drums, letting a brake shoe get jammed.

 

[Spudfarmer]

Hi bb770! Thanks for the reply. These little 770's are quite the tractor and have all the bells and whistles. Gotta love 'em and with so many features, there will be repairs. So it goes.
I just had a thought as I read your reply: I checked all the springs to see that they were not broken, but I did not have a schematic that shows ALL the springs. I may have lost one. I will check that out. Also, all four wheels lock up, not just one.
Thanks for you help!
Spudfarmer

 

[bb770]

If you go to John Deere Parts, you can look-up drawings and part numbers for your tractor. I'm not computer literate enough to bring the drawing over here. I've had my 770 since 1989 it only has 550 hours on it.

 

[Spudfarmer]

Misdiagnosed--Parking brake is working (light flashes sometimes when it is off, but the mechanism is okay). The problem is somewhere else. This morning as I was in 2-wheel drive, I noticed that the front right wheel locked up for sure (right/left as sitting on the seat). The rear wheels continued to spin. I don't know if the left front locked or not. It almost looked like the right front wheel rotated backwards but it was early and I may not have been completely awake. I pushed in the clutch, waited a few seconds, and let out on the clutch. The front wheel (or wheels) unlocked immediately and I continued on in 1st gear. About a minute later, the same thing happened. I don't know if it does this in 4-wheel drive or not. I want to love this tractor, but Bad John doesn't seem to be returning my feelings. Now with my problem moved from the parking brake to ???, does anyone have any ideas? Or, time to trade 'er in!
Spudfarmer