Conductive grease?

That age-old problem of conflicting requirements. Someone's cherished domestic amp from 1983 uses slideway ribbons from the front panel to pcb mounted slide switches. I last saw this amp 5 years ago, loss of some function switch function. Same problem this time. Then it was a build up of black copper sulphide/ silver sulhphide? forming a black insulated layer , eventually too tough for the sliding phosphor bronze contacts to break through. The structure of the switch with 1mm gaps between the static contacts means it needs lubricant to overcome the sliding contacts slipping in and out of these gaps or I imagine they are likely to buckle and jam. Sliding contacts seem fine, they retract fully on removing from the static pins, no distortion. No trace of corrossion this time, good to see that worked, but the lubricant I used probably did the same as the original sulphide and blocked contact , thickening over time perhaps. Previously I cleaned out all the corrossion and ex-lubricant goo and then used a mixture of silicone paste and graphite, only signal levels, so not too concerned about stray graphite conductive paths, >100Kohm or so. Anyone else any ideas? I was thinking this time to totally clean out , rotate contacts 180 degrees and use a liberal amount of graphite only in the recesses as a dry lubricant. Then when switch is resoldered into place surrounding the whole switch with a membrane to keep the graphite inside. Or much the same as before (5 years is not too bad any way) but less silicone grease in the mix proportion. Too little grease and it will not stick to the contacts. A different sort of grease perhaps with the graphite . The conflicts are Keep corrossion at bay lubricate sliding contacts retain electrical conductivity in static posistions sliding contact pressures cannot be increased or they would score into the silver plating or jam and then buckle long term material stability