if you absolutely cannot loosen the screw on the linkage by hand, hit it with a heat gun. be very careful and start w light heat, and focus the heat only on that screw. it will melt wires and damage other things if done haphazardly. a few back and forth's between the heat gun, and attempting to turn it, should do the trick to get it started.

Using a 1/4 in socket is much easier than the flat head screwdriver.

i think he's referring to the female hex nut that holds the linkage to the flipper shaft. you need to use an allen key.

also i'm pretty sure this is the proper post replacement, unless they used one with a shorter base to compensate for the flipper baseplate covering it.
https://www.pinballlife.com/2-14-tall-metal-post-with-threaded-base-and-female-threaded-top.html

Use a 3/8 inch box end wrench. No heat needed. Just need the right tool.

Every pinball toolbox should have an assortment of small combination wrenches (boxed end and open end) in their toolbox. $22 at Harbor Freight.

https://www.harborfreight.com/fully-polished-sae-metric-combination-wrench-set-32-piece-68854.html

If you took it off with vice grips, you should order a new pawl too. Mangling the nut with vice grips is going to make it tough to retighten properly. That nut has to be very tight (as you've noticed) to keep the flipper in the proper position.

you can't use a box end wrench. stern uses a socket head bolt that screws into threads on the vice. it's not a standard nut like used on BLY/WMS. you need an allen key (or apparently vice grips)
yikes (resized).jpg

Right. He (and you) said hex screw when he should've said Allen screw and I was thinking WPC. Hex screw generally means hex head screw.

Can't believe Stern is still sticking with the Allen screws. Also, for future reference, if any Allen screw is too tight, use something like a nut driver (anything sturdy and hollow in the middle) on the Allen wrench to give you more leverage. In tight quarters, even a little extra leverage is usually enough to get them loose (or tight). Allen screws rarely strip, just need to add more torque.

yep. sorry for the bad terminology. but yeah, stern still does this setup. maybe for patent reasons? just my completely uneducated, out of the loop speculation. but i actually replace all the stern pawl/linkages with WPC once the factory one's give out. much for this reason.