Mickey2

The screw will loosen, usually withing a couple of days with repeated oilings. The on on my 201 took 2 1/2 years, but it is my personal record lol. Another stuck scew loosened after three weeks of oiling and just letting it seep in there. There are spray cans with something that will make your screw freezing cold, it sometimes freez it up, you could try heating it with a hair dryer,... Is it completely stripped? Then you might as weel drill it out, but be careful not to ruin the threading in the clutch knob itself. I don't think this screw is easily found by itself, you might have to track down a replacement clutch knob or hand wheel set some where to get the screw.

leonf

I wasn't trying to worry you. There are options besides unscrewing that screw, but they do involve ruining a part or two. I don't have a 15-91, but I just glanced at a treadle head. If one is patient with a file, one could file down the other end of the screw that makes contact with two of the three ears.[ATTACH=CONFIG]577250[/ATTACH]

Not easy to get to and you will have steel powder residue, but it would be possible. Unless your potted motor is really in the way. try the gentle ways first.

You'll get it running.

Leonf

OurWorkbench

NZQuilter - can you show picture of screw? Another suggestion for a stuck screw is to put a wide rubber band across the slot and then tap the screwdriver into the covered by rubber band slot and see if it will turn then?

Janey - Neat people never make the exciting discoveries I do.

NZquilter

Thank you all for your advice and encouragement!!

Here is a picture of the screw. I tried using a rubber band, with no success. Maybe I'm too impatient. My 3/16" screwdriver can't grip it anymore and I fear the more I try, the worse I'll make it. My DH suggests leaving it with the PBblaster for a few days, then trying again.

I found some balance wheels and clutch knob sets on eBay, so at least I'll know where to go if worse comes to worse and I have to drill it off.

This machine was never intended to be a huge project My fixer-upper is my White Rotary treadle.

Mickey2

It looks like it's within doable, and I'm sure it will loosen. Have the machine out on a table and treat it gently. Oil, let it work over night, maybe couple of days then try again. Sort to clever tricks, maybe try a different oil, don't worry it just takes a bit of time and effort.

bkay

If I understand the terms correctly, if it were stripped, it would not stay in there. You couldn't screw it in because all the little ridges were "stripped". It could be cross-threaded, which means someone forced the screw in there crooked, or not straight with the ridges. It could also be possible that someone replaced a sewing machine screw with a regular screw, which would result in something similar to the cross-threading.

Just in case you don't know, sewing machine screws are not standard screws. That means the spaces between the ridges and the pitches of the ridges are not to the standards set up in the late 1800s. Sewing machines were already being manufactured before the standards came into common usage. So the sewing machine manufacturers continued to use the same screw standard they had always used. The moral of the story is keep up with your screws or pay $2.00 or $3.00 each for them from the old sewing machine guy.

Your problem is most likely that the screw has never been removed (or it's been a really long time) and it's just stuck. Get that PBblaster. It worked for me on three old Kenmore machines I was trying to part out. (I boogered more screwdrivers on project that you can imagine.) Use a screwdriver with a substantial handle that fits the slot exactly. If you have to buy one, take your sewing machine screwdriver to the store with you so you can match its width and length.

bkay

leonf

Oh yes, thanks for the pic. This is a whole lot of hopeful. Previous suggestions are on target, and Bkay's description of stripped and cross threading are good. It would be really hard to cross thread a dinky set screw, but Igor may have been there in your machine's previous 50 years. With a little rubber hammer I'd be tapping on the end of the screwdriver while the base is in the slot of the screw. Vibrations can help.

marshaKay

After using the oil, try putting a rubber band over the business end of the screwdriver. That will give you extra "gription".

OurWorkbench

Another thought about PB blaster is re-position machine and apply from back side and let gravity help oil/penetrate from the other direction.

Janey - Neat people never make the exciting discoveries I do.

Mickey2

Lots of good tricks mentioned now.

Spray can stuff like PB blaster penetrates just about any hint of a crack or space, even horizontally. Screws can still be subborn, so I guess it's about letting it seep in and do it's work. Sometimes I have had luck by switching to a different oil. I usually have some kind of spray can stuff around, the basic oils I use tend to be Triflow or Finish Lince Ceramic Wet Lube around. You should in theory do very well with the stuff you have mentioned; PB blaster and the basic sewing machine oil.