clutch pedal stuck

Trying to help out a friend with his 2006 335 peterbuilt he uses for his roll off container company. This morning he went to leave and the clutch pedal would not return to the disengaged position. He pried it up and it went back to normal position but as soon as he pressed it again it stayed down. I climbed under the truck and everything looks normal all linkage is connected. My thought was maybe the fluid is low in the resivoir. Please help if you might know anything.

 

He called a heavy equipment mechanic to take a look at it. Thanks for the reference point to look at.

 

A bracket under the cab that the linkage connects to broke.

 

There are two rivets that hold the bracket in place under the rubber floor mat. Over time those must have broken free which allowed the aluminum bracket to break free. The heavy mechanic lifted up the floor pad and drilled two holes and put bolts through with nuts under to hold it in place. Worked good enough to get the jobs done that needed to be done today. My friend also owns a 2002 f 550 that he used with a 5th wheel trailer to pull roll offs and his driver came back from a trip with half of the serpentine belt missing. Luckily there was half still wrapped around the pulleys so he was able to not need a tow back to the yard.

Not a good day today for my friend.

The heavy mechanic guy can't get to repairing the peterbuilt for a week because he is so bisy. He did mention he might need to pull the cab loose to get under there to weld the bracket back in place. There is a 1/4" misalignment now and the first gear grinds when going in. My friend drives down the road without using the clutch but to take off he needs the clutch.

Thank you all for the ideas. It does help to have some idea where to look when dealing with something I have no experience with, but it looks like I will be getting some experience with this one.