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.