Thanks Edward. The push rod on the master cylinder has lots of free play so its internal. if anyone has a book for an older model 5000 lb Clark propane ride on ot would be greatly appreciated. My email is [email address removed]. (EVEN POTOS WOUD HELP)

ahh, the fun of "inboard brakes" this brake system will require considerable effort to get into, and pretty much explains your reluctance to have to dig into the brakes.
at this point I would want to insure that there really is enough free play in the mater cylinder rod to be sure the master cylinder is allowing all the brake fluid to return.
Getting into this brake system is not a fun or trivial job, and not a good one for anyone who has not done one before to try without either someone who has done one before, watching to make sure no one gets hurt (and to help "man handle" the assembly which is close to or over 100 pounds) or at the very least has the book to see what they are getting into.
If someone does have a book for this truck, and they would be willing to share the parts about the brakes with you, they will need an e-mail address, and you can not post a properly formated e-mail address on the forum, but you can add it to your profile.

many thanks for info, I pulled the wheel but there is just the shaft with tapered bearings and a gear which drives the wheel, no brakes? Where are they

pull the wheels off, don't try and do a 1/2 way job with forklift brakes, just bite the bullet and do it right, one time only. you may only have to sand off the rust, (if it was me I would change the wheel cylinders, after a few years it will need it) but wouldn't be better to be sure than to have someone hurt?

you do have free-play on the shaft that pushes the spool into the master cylinder when it is "at rest", correct?