This is Kathy's new sister, Liz. Who was a gorgeous movie star in the 1950's with shiny black hair and violet blue eyes (like the shiny black finish and blue badge on this gorgeous machine)? Yep... :)
Liz and Kathy refused to make it easy for me to choose.
Liz: A drop dead gorgeous machine who makes a perfect, beautiful stitch. I plowed her through a swatch of 16 layers and the stitch was absolutely flawless. But she sews much more slowly than Kathy. The first side by side test I did, she was 25% slower. Then I tinkered, adjusted and re-oiled BOTH machines, ran the test again, and she was 40% slower! But I'm not sure if the one speeded up or the other slowed down. ????
Kathy: quite a lovely machine in her own right, but can't hold a candle to the dazzling Liz. Should I rename her Debbie? (Sorry, bad joke!) The choice at this point would be fairly easy - all other things being equal - except that Kathy is a BEAST of a machine next to Liz. (To carry the bad joke further, who has their money on Debbie Reynolds in a cat fight between those two?) And honestly, If I had only Liz and didn't run her next to Kathy, I'm not sure I ever would have known there was an issue.
Maybe there is still hope for Liz to reach her full potential. Again my disclaimer: I am not an expert at SM repair, not even close. I am an amateur hobbiest tinkering around and figuring it out as I go. (That is half the fun!) So in the pursuit of figuring out the discrepancy, I filmed the motors running, just trying to visualize what could be the difference - is it in the motor itself, or is there some lack of transfer of the full power of the motor to the machine? (I have inspected, tweaked and adjusted everything I know!)
This is the 1951 motor running without the belt:
Here is the same motor (1951) running with the belt:
This is the 1956 motor running with the belt:
Not sure if this will clarify the problem in any way, but I'm working on it!
Meanwhile, I guess Liz can snuggle in for the winter, at least. (Market on eBay is sluggish for FW's right now anyway. Oh well!) And maybe if a "certain someone" ..... *ahem* DH .... were to "forget" that I promised to sell this machine then maybe she can stow away a little longer. :)