Walker Jackshaft removal

[bbaird1981]

Hey guys. I'm new to the site. I have a MT 20hp Walker mower that needs a new jackshaft. I already bought the part and attempted to install but came across an allen bolt head that is pretty hard to get at. Any help with this is greatly appreciated.

 

[mechanic mark]

Penetrating oil to let soak along with a piece of allen wrench stock if it's in a tight space using a small crescent wrench or vice grips. The easy way would be a ball peen hammer & a good sharp chisel, then just replace bolt. Can you post a picture?