Like Viagra stiff, but I really wouldn't know anything about that. So I did a search and found the suggestion to clean, clean and clean and then lube. Mine were already very clean and unlubed. So I did that. I did not want to keep putting the whole seat in and out so I pulled one of the seat rails from the bottom of the seat and tried it out. It moves easily on the frame in the car. When I went to put the rail back on the seat, I noticed there is a ton of slop in the holes for the mounting rail. I don't know what the set rails are supposed to look like since most everything on the car has been touched before.
Then I thought maybe the problem all along is that the rails are not straight or adjusted properly on the seat to fit the frame.

Is the only way to get the rails set to the frame to take both out of the car and flip it upside down and slowly tighten things to get it aligned? These are non-stock seats but the rails and frames appear to be stock.

Any scraping on the rails evident? And did you repaint? Paint thickness can easily be an issue if overdone.

yup remove both and fit the seat to the rail

The rails on the seat are unplated and no obvious wear marks. The frame is a black paint maybe, very thin coat and no obvious wear marks other than a little on the top where the seat rails slide. It all looks normalish. I will assume the larger holes in the rails are to make it fit the seats.
I'll go ahead and remove the frame and fit it to the seat and put it all back together and see what happens.

RRC is calling and these are really fighting me. The rail with the handle on it appears to be mostly stock. The other rail has had the mounting holes in the rails ovaled out. They are both using non standard hardware, bolts with larger washers. I borrowed another set of rails and tried them. One or two of the holes does not line up. That might explain a little of the hole enlargement, but someone really went to town on this one. They each slide through by themselves but when I get them together and tighten the hardware, they either get really stiff, or lock up. I broke the adjuster handle off trying to release the catch and push down on the frame.

They are out of the car but annoying to work on from the floor. Any more tips. I can put a stock seat in just for the rally if I have to.

Wish Viagra worked like that for me!

Could be the non stock seat rails do not want to play with the fixed rails in the car.

The seat rails and frame are stock, the seat is not. One of the frame rails was drilled out at some point. Not sure if it was for this install or they just grabbed what was on the shelf and made it fit.

I am going to mount the frame rails to the seat frame and test fit it on the bottom of the seat to see if I can get all the mounting holes to line up.