Need Help Seal El 54 help

Hello everyone.
I have a seal model el 54. The gear that moves the chain and makes the rollers move is
slipping from the shaft. I was able to tighten up the two set screws before and it would work fine for a while, but now I tighten the set screws as tight as possible and the gear is still slipping.
Does any about have any advice? thank you

 

Here is a picture https://flic.kr/p/PYZkDG

 

I thought about welding it also. lol, but it would be pain in my rear if I ever had to take it apart for something else.
Please post the pictures. thank you.

 

Before I weld it . I just wanted to know if there is a part that can be replaced or repaired.
I tried calling seal but I could not get a live person on the phone, still waiting on call back.
Thank you for your feedback, it is much appreciated.