Singer 107W3 stitch length adjustment

[BruceBrown]

My 30's era machine, just gifted to me, sews 12 stitches/inch when the balance wheel dial is on 6.  Despite the diagrams on the W1,3,5 user's manual, there is only one adjustment screw port on the head.  When I removed the covering screw I encountered an adjustment screw with a screw driver slot so shallow that even a custom-made driver won't turn it.  I imagine I could drill the screw and back it out with a left-handed thread extractor drill but I'd like to know if there is an easier (sic) way.  Does anyone have experience with this problem?

[DonInReno]

Old screws that haven’t been turned in years can be held up with old dried oil.  A little heat can go a long way.  I’d use a propane torch and heat the screw only until a drop of water wants to boil - that’s often enough to loosen up the oil, and 210 degrees isn’t hot enough to damage any heat treating.   

[Constabulary]

Probably the stitch length regulator is gummed. Do you have a manual? There is a good X-ray picture in it showing the stitch length mechanism. W/O knowing details of your machine I would remove the  screw A + B and also pull out the spindle L. and drip in some mineral spirit (what ever you have, kerosene, paint thinner, white fuel...) and / or apply heat with a heat gun. But maybe the machine is just set to a shorter stitch length and you can readjust it - see picture & last paragraph  - hope this helps.

Hopefully the threading on the spindle knob or hand wheel are not busted.

Edited October 27, 2019 by Constabulary

[Constabulary]

aaaaah - sorry - seems I was too fast with reading - seems you figured it and you have a manual... sorry!