I bought a summit big boy chain break on ebay. After I modified it the thing works better than the park... My park was pretty tough except the pin pusher brads on me every time I use it. The steel is too soft or I wind it down way to tight.
The summit hasn't done that yet but all the chain guides broke off so I ground them down to nothing. Now I just line the chain rivet and the plunger up by sight and it works great. I always start the replacement of the rivet with a pair of pliers then use the plunger to press it home. Works every time.