Purchased this used trinidad 14A, and after opening it up I noticed the slot screw on the back of the clutch lever is broken in half. I tried to remove it but no luck, should I send it to shimano? If I had the parts I could repair it. But cant get that screw out
Try drilling out the screw carefully using a dremel tool with a very small bit
Try getting some PB Blaster in there for a few hours or overnight. Then try a small extractor. I've tried extractors, but without much luck. Porthos recently posted on a stuck screw he removed with an extractor. Check his post. If that doesn't work, like stated above, you will likely have to drill it out. If you have to drill it out, I would check parts availability first. Some of the older Shimano reels are hard to find parts. Keep us updated.
here is your schematic. what is the part number of the screw? part number 285?
https://www.reelschematic.com/wp-content/uploads/schematics/Shimano/Trinidad/Shimano%20Trinidad%20TN14A.pdf
if you can dremel off the head completely, you could pull the clutch lever out and the stud would just stick out. then a pair of pliers could help you remove the screw. you'll have to order a new screw, first, or figure out what size it is and find a stainless steel metric screw that matches.