My 445 tractor has started to become somewhat temperamental. When I put the key in the tractor to start it, I typically have to jiggle it a bit to get the instrument panel lights to come on and to get the fuel pump engaged. Sometimes, I have to jiggle the key several times to get the lights and fuel pump to engage properly. When I turn the key to the start position to get the starter to engage, the tractor will start, but when I let off the key, it dies. I have to perform this ritual a few times to finally get the tractor to run properly. It seems that the ignition contacts may need cleaning. Is this even possible or might there be another cause to this issue and how might I fix it?