Uwe wrote:

Fleetwing wrote:

I am trying to remove the four screws on the back of an SM-7 to get at the tab brake -- I am pretty sure they were painted over at the factory when the machine was assembled.

Those screws are not recessed, but they are prone to rusting if the machine was stored in a damp location for any length of time, so I'm willing to bet that it's rust that is giving you a hard time and not paint. I've never had issues with SM7 covers when the machine was in good condition, but have had to use quite a bit of leverage to remove ones that slight rusting.

Thanks -- they don't appear rusted at all, but rather painted. The ends of the screws likewise, no rust. I did apply penetrating oil, to no effect; I'll try again. Given the state of the machine when I got it, with various internal screws/parts having a light rust coating, I expect there is some sort of corrosion on these screws. Would that they were hex-shaped; a nut driver would be ideal here. As it is, I'm afraid of damaging the slots. 

Ordered a 4mm wide screwdriver with a 0.5mm thick tip, a longish shaft and a handle with a good grip. This was the widest 0.5mm screwdriver I could find. The screws measured at 2.9mm using a vernier and the heads at 4.8mm. This is presumably translates to an imperial size of some sort.

Anyway, screws have been soaked in Plusgas and tapped every day for several days and this morning when I tried the new screwdriver for the first time one shifted & I was able to remove it! Hurrah! Now for the other one.

I also repair fountain pens & I've learned that patience and in the case of pens heat & soaking works wonders over several days. The key think is patience. Don't rush at it like a bull at a gate.

Little victories like this are always satisfying.  I usually like to put on a big band or oldies record when I scored a repair "hit" on a typewriter.