Highpower 750 mechanical timers are one of the staples in the industry for this type of application.  They are used in both Highpower pushbutton assemblies and assemblies from other manufacturers.  These timers use a controlled flow of air to regulate a timing cycle of a microswitch.  While reliable, dirt and sheetrock dust can enter the assemblies air mechanism and trip up their internal air seals.  To fix in the field, remove the brass adjustment screw and then blow compressed air through the adjustment screw hole.  If that does not get the timer working again, then you have an issue and you should order a replacement timer. Even better, you might want to just order an entire fresh pushbutton assembly from our store. 

Note part number matches up with the brand of assembly that you have.  When replacing these in Highpower assemblies, screw them into the un-actuated assembly until they actuate, then back off half a turn and secure the lock nut with a drop of thread locker.  Highpower will also service a Highpower assembly if returned to the factory for the cost of the replacement part. Other brands have different procedures. Contact us if you need help with the timer part number as we have extensive knowledge of this family of product. 

Usage reference:

750-1000 - BEA, Highpower, RCI full size pushbutton assemblies.
750-2000 - Industrial applications.
750-3010 - Schlage pushbutton assemblies.
750-4000 - BEA, Highpower, RCI mullion pushbutton assemblies.
750-4100 - SDC pushbutton assemblies.
750-4000C - Camden pushbutton assemblies.

Designed, machined and assembled in USA with domestic and foreign components. All models except for 750-3010 are UL listed with MET Labs for UL508, CSA C22.2 #14 File number E113051.  Brands are trademark of their respective brand holders.