Cracked PCB

this was one of those vintage keyboard pcbs, ibm, apple stuff idk 
those old boards used one layer pcb which means 1mm cheap pcb material plus its like 20+ years old so not as solid as todays stuff 
this one cracked resulting in traces cracking 
pretty simple fix just scrape of the excess and run a wire through each trace 

now the main issue was the crack itself as any stress on that area will crack the traces again, the pcb is already big and flexible
fix was to first solder mask the exposed traces then epoxy the whole area, top surface, inside crack and a thin layer on the other side, if the crack is invisible after the epoxy then it means the pcb fused properly with the epoxy and its a good adhesion/bond.
even if u flex the pcb the stress will be evenly spread across the area instead of that specific crack 

make sure u prepair the area u are planning to epoxy/soldermask, u need to properly clean and degrease it like no flux/oil or anything, personally i usually clean it with ipa first then final acetone wipe with a clean cloth.