Won't power on

Was getting a little iffy about powering on & then failed completely. Recharged set of batteries tested in a second 5050 work OK. Contacts in camera spotless and batteries making good contact as far as I can see. So I suspect the switch itself has failed: is the mode dial assembly dismantle-able so that the power switch can be fixed? Is it likely to be fixable? I know how to remove the mode dial assembly. I have dismantled & repaired other cameras before & have suitable tools for the job so, please, no suggestions about taking it to an "authorised repairer" (totally uneconomic!).