Does the button on the left side of the lens mount that turns the light on still turn the meter on?
The contacts on the shutter half press were one of the few weak points on that camera, when they start to crap out there are fiddly ways to get them working again that sometimes work but you are probably better off just sending the camera off to Eric for a CLR with a note for specific attention to cleaning the shutter half press contacts. That would take care of all other concerns as well and give you another 20 years of service.
I actually expect that on every used Super Program (Super A) I buy, its that annoyingly common by this age and I like to know that everything is good to go anyways so I always factor a CLR into the purchase price.
EDIT: Sorry my brain was on vacation, perhaps in England where I just noticed you are located, you will want Robin, not Eric on that side of the the pond.
http://harrowtechnical.co.uk/