Mark vi friction on the upstroke

[fullofdays]

My mark vi has an excessive amount of friction on the upstroke. It is not lube mechanism related. Anyone know this machine and what could be causing the friction? I am thinking it could be the bolt thru the piston connecting the handle but am not sure. The bolt connecting the lube arms actually sheared due to the friction.

http://imgur.com/btYvYv5
http://imgur.com/lmAUG43

[6bg6ga]

All you have to do is gently loosen one bolt at a time and try it and see which one affects the drag. The one I had a little too much tension and I took care of it. Over all its one great machine.