[G4] Mirror Drive on/off Button - Prone to Failure?

[jonny]

A new project:

I have a mirror drive, 1.25 dual MDD that I plan to use as my main machine.

I'm having trouble getting the on/off switch on the mirror drive to 
turn it on every time.

I can feel a subtle click (most of the time), but often, it won't 
turn on.  Right now I'm stuck.  I cannot get the MDD to turn on at 
all.  The machine has power.  And a new power supply.  OSX hardware 
utility tests 'Passed' all hardware components.

Just finished cloning one machine to the other.  Running OSX 3.9. 
Cannot restart MDD with switch button.

Is it possible the switch is the problem?

Any suggestions will be much appreciated.

Thanks.

Jonny