1990 Cincinnati Sabre Acramatic 850 controL MC

Recently purchased a rescue machine from a retired machinist. It has been sitting in his garage for the last 6 years. I was told that the tool changer pneumatic cylinder needed to be replaced or repaired. I came to find out that he disabled the TC some how. I found a switch on the back of the machine that states service. When I power the machine up with that switch turned on, I get a few new options to look at but I still do not see the magic (TC enable) button. I knew it wouldn't be defined that easy but does anyone know how I can reenable the tool changer? He does not remember how he did it. He thought he did something on the parameter side of the control but does not recall flipping a switch in the back to access the parameters.
Thank you for any help.
Tom