If you have a shop in your area that rebuilds starters and alternators, you can check with them and get a solenoid rated for constant duty. I had this same problem and the solenoid from Ski-dim only lasted for a few months then did the same thing. The continuous duty solenoid has been in the boat for 3 years with no problems. It installs just like the original part, except for the mounting holes. Put in a battery switch so that you can disconnect the battery just by turning the switch for emergencies, I put mine next to the battery box.
agetech
89 Comp
Restored to "Better than New"