I am not sure I made that clear with my description. The worn hole is in the end of the arm that is attached to the master cylinder as seen in the photo.

The two shinier black arms are repainted 40 year olds with no wear and the flat black is a 10 year old with wear.

All excellent suggestions and diagnostic advice!

I'll separate mechanical and hydraulic components later this week to further isolate the problem. Terry may be on to something with the pivot shaft hole as I've noticed a bit of play as I begin to apply brake pressure.

I had a similar problem not too long ago and it turned out to be a worn pivot shaft hole on the pedal arm.

It would bind and not allow full return, then I could either lift it as described or it would pop back with a "thunk" after a minute or two.

If you separate the mechanical action from the hydraulic action as described you will find out where the problem is.

Terry

LHD or RHD ? I'd think the master/booster are built together. I have worked on a bunch of these and always find brake fluid in the booster. The rear portion of the masters always have had rust pits in the cyl which honing would do nothing for. A new master is cheaper than a rebuild and sleeve job. I rebuilt a booster and it is a bear of a job. Like mentioned check the pedal pivot. Steve (CTR)

As it is a '90, you have the servo'd master cylinder. To figure out what is going on, pull out the linkage pin behind the servo (on the vertical pushrod), and try moving the pedal. The pedal should be free and easy to move up and down. Same with the linkage going to the servo; this should now move freely.

Check this, and report back.

Personally, I've had the main pedal pivot bind up before now. Exactly as described by the OP.

I think I would pull the pin that connects the pedal to master cylinder.  Then you can confirm whether its the pedal pivot or the cylinder that is sticking.

Cheers, Ian

I have a 90' mini with sticking brakes. Sometimes when I press the pedal 1/2 - 3/4 of the way down the pedal sticks in place as I take my foot off the pedal. I can make it release by lifting up gently on the back of the pedal with my toe or pushing the pedal all the way to the floor.

Things I've tried: - flushed the old fluid and bled the brakes - PB Blaster'd the nuts and linkages connecting to the master cylinder - verified the front pads are in good shape

Any suggestions for what to check next?

At least I'm learning about trail braking!