'85 VF500F start issues - does not crank

Hello everyone, I am having an issue with a "recovered" '85 VF500F. After a,valve adjustment and carb cleaning, I managed to put it back together and started it successfully. Had it running ok for about an hour while adjusting throttle, pilot screws, etc. Then after a couple of hours it does not crank. There is no click from the starter solenoid or any sound from the starter. The lights dim while engaging the start button but nothing happens. Checked all fuses including the starter solenoid one. Any advice would be greatly appreciated. I was reading on an older posting about attempting to manually engaging the starter with a screwdriver, how is this done exactly? It almost looks like a clutch safety switch. The key is on. Bike is in neutral (the neutral light is on). The wheel turns so it is definitely in neutral. Thanks in advance!