Don't need an expensive main spring vise. The standard one used by many is $25.95 , from Log Cabin Shop catalog #50 inv. # 20MSV1. I use two , one with a small modification thinning the upper jaw so it fits the odd spring. Also , let's visit Removing the hammer from the tumbler. An $80 hammer puller .......unnecessary. If you have a bench vise , remove all the internals w/your new mainspring vise. Remove the hammer screw , find a small punch that fits loosely into the bottom of the hammer screw hole. Open the bench vise jaws until the inside of the lock plate lays flat on top of the jaws , and the tumbler is free between the jaws. Insert the skinny punch into the tumbler screw hole and administer a light tap w/hammer. Done. Catch the tumbler in one hand , so the fly doesn't fall into all the manure on the floor. Another useless tool is the $65 .00 hammer press. Installing a hammer can be done w/ the bench vise. Can be done w/a standard big bench vise with brass sheet metal jaw covers , but the easy way is to get a small 2" to 3" inch vise you will use anyway for other operations , like sawing out and filing inlays , etc. . To put the hammer on the tumbler , make sure the square in indexed to the tumbler in the correct position , and press the parts together. All this stuff is just good common sense mechanic operations. Think of what's to be done , and proceed w/caution , it won't cost you a dime in broken lock parts......................oldwood
