I rebuilt my 1.7 MPS a while back and am now looking to calibrate it. I followed pbanders' screw removal advice religiously and simply cannot get the screw out. I got it to break loose and now turns 90 degrees but farther than that - no way! All epoxy is gone and I have used a lot of heat, penetrating oil and patience. Even bought a 5/8" wide drag link bit that fit the slot perfectly, but even with a 1/2" drive breaker bar it won't budge. Got so frustrated I even tried my impact screwdriver and a hammer.

I'd hoped to get this done without taking the MSP apart again, but it seems that drilling it out may be the best last resort. I have the replacement screw from the TR tuning kit but am afraid the fine threads in the hole will be easy to mess up if I try to cut the old one out.

Would appreciate any ideas or techniques that have worked for others.

Thanks,

Ron

The outer screw should have been removed during the initial rebuild, this is now out of sequence.

Heat, heat heat. Epoxy permeates down into the threads. Heat is the only method. And you will likely cook the gasket around the diaphragm requiring that work to be redone. The outer screw should be removed by screwing it into the case not out of the case. You may also need to chase the threads with the correct tap to clean them.

Thanks Jeff - yes, it was an early newbie mistake to not realize that calibration would be needed so I only did the rebuild. Lesson learned, but thankfully the new diaphragm and paper gasket are still in great shape.

But, FWIW, I was able to finally get my old screw out and came up with a method that might be of interest to others. I know it's supposed to be easier to screw it in than out, but I had managed to mushroom the screw around the edges of the slot and there was no way to push it through. So, looking at the inside, I though of trying to turn it from that end and found that a 5/16 - 18 bolt can be easily threaded into the plug. Use a bottoming tap to increase thread grip. Then I attached it to a piece of metal to keep the body from spinning. This made it really easy to apply heat while turning and it came out without much fuss. BUT, try this at your own risk because perhaps I was lucky. In any case make sure the bolt is perfectly vertical and not binding on the hole in the metal. It might be possible to mess up the threads if there is any side load.

Ron

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Creative but effective! FWIW the outer stop can be removed easily enough and reused 99% of the time with suffient heat and patience to not mess up the slot.