This sewing machine has all metal gears that drive the needle up and done through the material being sewn. Machine has a label that states the sewing head is warranted for 25 years. The feed dogs are also feed by metal linkage. There is no rubber belt except for the motor drive belt.
There is one plastic gear with white grease on it that moves the needle side to side. The thickness of the material being sown has no effect on the side-to-side motion, because the needle only moves vertically as it enters and exits the material being sewn.
Machine has been cleaned and oiled.
Bring some material and try this machine out.