Dash light problem - Civic 1995

I have a 1995 1.4i base civic (RH drive, UK built). I have a problem
with the rear screen heater push switch and the fog push switch lights
on the dash. When I switch the lights on, the rear screen heater
switch and the fog switch lights are intermittent. Most of the time
they do not work but sometimes while driving along they come on then go
off again randomly. The ashtray light is same; sometimes on, sometimes
off. I have checked the fuses both under the dash and under the bonnet
but have found no problems. I have also tried to see if there is a
loose connection somewhere but have not been successful as it is
difficult to get behind the panel. Just to note (as I noticed in other
posts), I changed the stereo recently but this was a straight swap -
no further wiring required. There is also no dash light dimmer on this
model. Has anyone else had similar problems or have any suggestions?

Thanks