distributor vs patina on contacts

first sorry fo my english
The problem is:
when I left car for a week or more in a garage, specially when humidity in air is high, I often can't start engine after that. A proplem is always this same: every 8 contacts under distributor cup coated with patina.
Remedy:
I slide contacts with mild sand paper and reinstal cup and start engine. cylinders starts one by one, after couple mils all 8 run together. maybe is easier way to prevent this for longer time?. do You have that problem too? I have delco-remy hei distributor.