Spring wound timer problems

[Creek]

I have spring wound timerson the hot tub jets in our athletic facility. I've have to replace the one on the men's hot tub several times a year because it doesn't turn off anymore. The last one lasted about a month. The women's get replaced 1-2 times a year.
Does anyone have any suggestions on what is causing the problem or possibly a different timer option?
The one I'm using now is an Intermatic FF315M 15 Minute Spring Loaded Wall Timer.
I'd like a push button timer but not finding one without a hold feature, which I can not have. Other option I see is build one myself.
Thanks
-Creek

 

[stevie3x]

what i do when installing or replacing an existing spring wound timer is replace with a 60 minute timer & drill a hole in the front cover apx at the 45 min area & put a pop rivet through the hole so that it cannot be turned past this stop, that is generally what causes those timers to break people using the spa tries to twist the knob past its intended set point