The HEI unit is so dependable that the advance weights will wear through the pivot pins before the electronics give up. I recommend looking under the cap every ten years or so. Buy a new HEI on ebay for forty bucks, get a hold down from Speedway for seven bucks (Part #91044030) and have a machine shop turn the factory hold down flange off, about twenty five bucks. For under a hundred you have a spot on dependable dizzy that you can buy parts for anywhere and with the plugs gapped at least 0.045 and up to 0.060 on old 6.5-1 compression engines it gives a fat hot spark that makes a lot of hard starting problems disappear.
