JIm here is the Diagrams to make that gizmo i mentioned.
Works a treat and is a one person thing , so you can work away in your shed by yourself.
Reason i made one ? ---- Did the same thing your dad did, but it was just me there, standing in the shed with a screw driver in one hand and my finger of my other hand jamed in the collar and spring, PAinful but rather than scream ( cause it freekin hurt) i spent the next 10 mins Quietly and patiently trying to figure out how i could get in some slack by just using my free hand. Took some ingenuity to get the spring down and my hand out in the end, Lost my nail. bUT BOY WAS I HAPPY TO BE OUT OF THAT MESS.
TRY THIS GIZMO ..... for under $10 !