Timing Chain tensioner

I recently bought a Mighty max and it has developed a sever leak in the front main seal area. I am having trouble taking the tensioner off of the timing belt. I took the adjustment bolt out of the bottom and the only other thing I can see holding it in is the bolt in the top part of the attached picture. It looks like an allen head but none of the allen keys in my set work and I don't think its a traditional bolt head.

Can anyone help me? This is the only thing hindering me from completing my seal change.

Eureka! So apparently what I thought was a bolt was a stud. No wonder nothing fit! For future searches, the hole is meant for a 3/8" allen wrench.