Pentax 67 TTL meter power problem

Hi

I recently got a Pentax 67 with TTL prism and I have a problem with the power switch.
The meter is constantly on and I can't turn it off. It measures perfectly ok, but does anyone have an idea how to fix the power switch, because like this it will just drain my battery super fast, won't it?
Would be great if someone has any help/suggestions, cause I'm dying to shoot with that camera!

Cheers

Here is a manual:
http://www.cameramanuals.org/pentax_pdf/pentax_6x7_pentaprism.pdf

thanks BobD
I already had the manual, but it's not really of any help... at least I could not find anything helpful relating to this problem. There is a lot of info around if the meter can not be turned on. But nothing about how to turn it off again...

In the manual:

“To save battery consumption, the meter may be turned off by sliding the switch to the OFF position immediately after you have made your reading.”

If it won’t switch off, then obviously the switch is defective. The finder needs to be disassembled to expose the switch so that it can be diagnosed and fixed or replaced if necessary.

Unless you feel competent to do the job, the finder will likely have to be sent to a camera repair shop for repair. A high-volume camera repair business is likely to have technicians that have seen this before, know how to deal with it, and know where to obtain replacement parts if needed.

Yes, I guess I will have to open it and check the switch and the components on the circuit board (maybe the capacitors..?). Unfortunately this will have to wait a little, since I'm "on the road" at the moment, and don't have the proper equipment at.
But it eventually turns off when I switch the lens to Manual Mode. (which is not the proper way either, I know...), so at least I found a (temporary) way to use the camera.

Does someone maybe have the service manual of the Pentax 67 and the TTL pentaprism?