Belt adjusting screw Necchi 537 FA
 

This is a bit modern, but it thought it might be useful to anyone else who opens up thier cousins machine. The marked screw is for adjusting tenion on the belt from the motor to the pulleys and from the pulley to the drive shaft (not pictured) It is a bit hard to hold the tension correct when you tighten it down. And a very important note. It is Left Hand Thread.If you have to replace a belt, be ready for a spacer washer and a slide nut to fall out.[ATTACH=CONFIG]613136[/ATTACH]