In addition to the shear pin instructions, there are a couple of things I "learned".
There are three parts to the "fix a stuck dock line" puzzle:
1. Side-Power employs a strange size fuse - expensive and hard to find. I first changed to an electrically identical "blue Sky" fuse - the entire assembly and spare fuses cost less than one Blue Sky and a spare. I have since changed to a circuit breaker - it makes no sense to use a fuse in this application - since there are times when you should be able to shut it off easily. Again, not much money from Amazon.
2. The shear pin is VERY DIFFICULT to change, at least on my 2010 Ranger R25. I had a stainless pin machined so it would not ever break again. Save yourself the grief. The fuse or circuit breaker can sized to protect the works, eliminating the difficult shear pin replacement for a plastic bag entrapment (for example).
3. The drive leg was bent the first time I had to change a shear pin. Back Problems triggered hiring Side Power to make the swap - and they never noticed the bent leg. Two weeks later when the pin failed again, I was recovered enough to do the swap - and swap the drive leg (not hard to do). Check your thruster drive leg VERY CAREFULLY, it should spin easily and quietly with the motor and shear pin out - if there is gear noise replace the leg. After careful examination, it seems the design of the leg makes it fail before the shear pin.
Remember, the first rule of boating "If it works, don't use it."