With the post, a careful hammer from underneath. There are no threads holding it in, just friction.

On the popper, try cleaning the shaft and the coil sleeve with alcohol, make sure nothing has worked loose, and make sure it has the correct coil per the manual. Also make sure the plunger tip is not broken or worn.

^ This ^...the first time I tried to remove one of these posts I mangled it pretty good with pliers trying to "unscrew" a post without threads

But the left gun popper issue...I hope someone else chimes in on this. It's my last issue with an otherwise perfectly running STTNG. For mine, it's not dirty (cleaned entire VUK and optos, replaced coil sleeve). It's not a worn plunger tip (replaced plunger). And it doesn't seem to be trajectory related as I have tried making slight adjustments to the coil stop. I swear it's somehow related to the power coming to the coil as I can actually feel that the coil doesn't fire as hard on the times where it doesn't make it up the VUK (sometimes it barely pops at all).

It really has me stumped (and extremely irritated).

Do what I did. I had the same problem with a post on my Dr. Dude. I used a small drill bit on a portable drill, made a small hole and then applied a back-out tool and spun the broken screw out of the hole. You can buy these tools at most hardware stores or Sears. Save the post! Remove the broken screw.

If youve removed the nut slide on an old rubber then lock some vice grips on it and twist/pull it out. I used this method to pull all the posts on my STTNG for tumbling.

The coil mounting hardware is only connected to the exiting weldment on one of four sides. Over the years of the coil firing, the weight when raising and lowering the playfield, possible use as a handle to grab onto if needed, and for me the number of times I probably banged my head or elbow on it... that gap on the other three sides can open or close a little changing the trajectory. I say bend it a little, it won't take much at all to make quite a bit of difference.

wish I could help. sorry -- looks like a pain to replace.