I don't know how to post it on this site and the site won't allow me to post my email address (thinks I'm advertising). I have an off-site toll free answering service (888.822.3748) Please give them your email address. This has fixed dozens of them. There is too much of a voltage drop going from the key thru all the safety interlocks and eventually going to the starter. The fix adds a relay, so the relay can handle the voltage drop and then puts direct power from the battery to the starter.
I had a Cub 7274 as my 'first big tractor' bought used. It developed starting issues a month after purchase. The battery would slowly drain out but at times would start. After extenstive tinkering and having other more mechanical type friends look it over. We found the battery leads especially the negative side was nearly completely corroded inside the insulation for about 8-10 inches (just one or two strands still complete). replaced both leads and did not have starting issues for quite a while by then found a reliable cub dealer couple hour drive away and discussed addtional problems -told me many problems for the cub were the 'safety interlocks' not being in precise spot so I'd have to jiggle and reset all the levers etc. Best of luck..
Having same problem as others. Now it has progressed. When turning key on, NOTHING happens. Won't even light up dash. Occasionally, lights come on, but as soon as key is turned, it goes black again. Battery tested, 12.9 volts. Took out and used to start my 2500 Ram pick-up no problem, so pretty sure battery is not the issue. Adjusted PTO levers for safety switches...nothing. No lights. Oddly, if you turn on the hazard lights or turn signal lights, they make strangge noise as long as key is off. Turning key on, all noise stops. Checked fuses on front panel, ok. Any help?