Thank you all for taking the time to reply to my query.
I have tried multiple lenses with the same results. The Seiko leaf shutter fires and adjusts according to the setting of the shutter speed dial.
I am not using an AE finder but the waist level finder.
I have both the user manual and the repair manuals and have read through them
I have the shutter lock correctly set according to the manual at the fully released position BUT with film in the camera (either 120 or 220 back), dark slide out, shutter cocked I cannot depress fully the shutter button to fire the camera. If I rotate the switch controlling multiple exposure to the multiple exposure setting and cock the shutter by turning the crank I can easily depress the shutter button and fire the camera. Upon returning the multiple exposure lever to the single exposure setting the old problem returns of not being able to fully depressing the shutter button.
This appears to me to be a mechanical interlock problem of some type rather than a battery problem but I will check as soon as I can get a new battery.
Now the other problem is that when the lens shutter fires at any speed there is no LED flash to tell me that the shutter has fired although I know it has and I have checked for proper shutter times.
So, two problems which may or may not be related.
I hope this doesn't mean it is off to a repair man but it might have to.