I repowered a 2003 Nitro 288 Sport with an Evinrude 225 Ficht, consequently I changed out the harness with a used OMC tach and wiring. The tach works very intermittently. It has the system check lights built-in, they work well, the tach only sporadically. I believe the unit is simply stuck due to corrosion. I attempted to disassemble last night, unsuccessfully. I sprayed PCB cleaner in the unit to try and clean it out. Does anyone know if the tach can be completely disassembled, and how to do it?