Is this a Thing?, E-Brake ?? Options

[pneuhyde]

So my last 914 had a non-working E-Brake. Everything was hooked up, it just didn't work and because the po had informed me of the situation I just never questioned it. When the body finally rusted away I found a roller to do an engine swap with. One of the things that excited me about this roller was that it had been converted to a 911 5-lug suspension in front and the words "New Eric Shea rear calipers & bushings with 5-lug hubs" jumped out at me.
How cool - Brakes that would actually work like they were supposed to, which to me meant an E-Brake, too. No more hopping out of the car and quickly throwing a rock behind the tire !!!
Well, to my surprise I still dont have a working E=Brake system. I adjusted the cables, then moved on to adjust the vent clearance and found this on the inside
adjuster.
On closer inspection, There appears to be nothing to adjust with behind the plug, and when I rotate the lever nothing inside appears to move and the piston does not extend to push against the disc

The outside caliper adjustement worked just fine,
So - "Is this a thing" to dismantle the e-brake on the inside of the caliper?