I have a 4610 that will not start with the key, I turn the key on & the dash lights come on & the glow plug orange light clicks off, but when I turn the key further to start nothing happens, so I hot wired it from the solenoid to the bat positive & with the key on it starts right up. I tested the key switch with a test light & all 3 of the connectors are lit up with the key on the start position but nothing happens I mean it does not turn over. I have heard that the switch sometimes gets dirty inside but with all the connections on the outside testing ok could it still be the switch or should I be checking something else out. Please any advice would be helpful, it is a pain to get in the seat &then have to get back off to start her. Thanks in advance for information.