There are no curbs in the mountains
If you turn the wheel you go into a ditch
We have ditches here: not curbs

 

You found one.
I've been dealing a same story as Yours around September last year. I had to replace a damaged driver's side cable and to re-adjust all. Thanks to Christine, who posted the procedure, I am sure You could find the topic and that info as well. I am way too tired atm, so excuse me..

Thing is the Blazer mechanism is not self adjusting. That should be self explanatory here. While replacing the shoes, I've expanded the mechanism as much as It was possible to fit the disc over the brake shoe. Then, I've went through calibration of the driver's side cable and equalizer: You jack up the end. Then tighten the driver's side cable until there's no slack. Then, You adjust the equalizer bracket till brake at both of th wheels is more or less equal. After all I parked upward the hill (driveway to my garage) and I found the brake slipping. Exactly as in Your case. I guess once after the brake boots settle finally, the gap between the shoe and the disc may change. So You'd have to remove the disc and make it over again.
Eventually I didn't. A busy life tho.

I bear in mind a recent story of my colleague, whose brake hydraulic line got broken. He found it while trying to stop with a trailer on his back. His brake pedal just went into the floor. Thing, that saved him that time was the emergency brake. My Blazer is old enough to have it done. I am aware, that what I do is just risky.

 

So you;re saying just like my mechanic that the parking brakes can't be fixed?
Somebody should kill the SOB who designed this crap.
I had a 77 K5 Blazer with drum brakes in the rear and the drum brakes also acted as a parking brake and it was fine... when you pushed down on the parking brake pedal, it had the same braking power that you had pushing on the brake pedal.
The %$#@ that decided to add a separate mechanism for parking should be shot.
There is no excuse and no reason for this pile of non-functioning crap to even exist.
If IF I could find an S-10 Blazer in a junk yard with drum brakes I will take the entire axle and put it on my truck just to get rid of this stupid brake that doesn't brake...
As far as I know there are no S-10's made with rear drum brakes: I wish there were.

 

Well, I am not convinced if that can't be done. I'd have once more to remove the disc. Check the inner surface and machine if necessary. Expand the regulator to a maximum possible size.
But yeah, that is frustrating, when You feel the high tension on a parking brake handle and then it slips... Apart of the rattling interior, this is another thing that hardly sucks in S10.

 

I'm pretty sure all blazers before 98 had rear drums. My 95 has a drum brake rear. The parking brake probably holds worse than yours, but I don't think my rear brakes are adjusted at all. I've been too lazy to mess with them, though

 

The gf 2001 2wd sonoma was drums...

 

You can't take an axle from a Sonoma and drop it into an S-10 Blazer
.... as far as I know, they're completely different body types.

 

"All Blazers before 98"
Do you mean S-10 Blazers or K5 Blazers?

 

"expand the regulator]... hmmmm
I don't have a photographic memory,
Si I don't know exactly what you're talking about
but I'll ask my mechanic if that could help it brake better/

 

S10 Blazers.