Thank you very much for this great forum, and I have just joined you, hoping to learn and share about this very interesting craft
I'm located in spain and English is not my native language, so I hope not to make many mistakes
In relation to servomotors in industrial sewing machines, I had the same problem when I purchased my PFAFF 1245... I thought that all servomotors allowed to sew very slowly, but I was mistaken. My machine came from the dealer with a servomotor Esda YX 800W, and its slowest speed was too fast for me... I talked to the dealer about it and he agreed to exchange the motor for a Ho Hsing G60 600W, as I read very good reviews about this servomotor, and the difference is like night and day...
I uploaded a video to YouTube where you can see the difference in speed between the old and the new motor:
I'm very happy with the new motor, and I still have not had any problem sewing different thicknesses leather with it, always using the ppropiate leather needles