Re: RG 760 wiring Seymour plus dimarzio
Fortunately. your Duncan is wired correctly. You could pull the red and white off of the last lug and tape them up (leaving them hanging). This may fatten the sound a bit, but you'll lose the capability of splitting it with the other pups.
Not knowing if your using the original switch or not, I'll add that the VLX-53 switch that came in your guitar may be damaged internally if it's been overheated anytime throughout the years. You should inspect it to be sure it's working properly.