rev counter dropping out

[doski]

hi all hope i got the right section im eyeing up a dtub which states the airbag light is intermitent (heard a lot about this on here something about soldering wires together or taking the bag out), but what most concerns me is he says the only other problem is the rev counter dropping out occasionally e.g. revs say 0mph when moving.

Is this a common problem? or at least is there a definate fix

i like the look of it but ive heard bad things about the electrics in a 306 and weas just wondering if there was a fix to this thanks