Hello, I'm new to the forum.
I'm restoring a Stern Hot Hand, at beginning I've had problems with MPU acid damage, but changed with a reconditioned one and then ok, I've got 7 flashes.
But not everytime, I've seen that after the 4th flash the spinning flipper begins to turn and then happens that pinball freeze and stops diagnostics (flash off), sometimes it happens during the 5th flash and then led stays on. When it goes to the 7th flash and the pinball is on, if i start a game when spinning flipper starts to turn it goes off again. Or few times happens that pinball starts ok and i can play normally.
I supposed a problem in the spinning flipper, so I've tried first to disconnect the lower right connector on solenoid board and everything goes ok, mpu starts correctly everytime. So I reconnected the connector on solenoid board and disconnected the little connector in the lower cabinet which goes from tranformator to spinning flipper motor, also in this case everything works fine.
I inspected spinning flipper relay and seems ok. All TP are in the correct values.
Can i check something else? Do you think something is faulty? Do you have any ideas?

Thank you so much for your help
Marco from Italy

Thank you so much! Problem solved, even after months...
Now I'm starting changing all fused coils, but still have problems with 1 amp fuse under the playfield.
I've installed bumpers first but fuse blowed all the time even with only one coil (i've tried one an once but blow all the times).
So i deconnected all bumpers coils and connected slingshots. In this case they work ok.
Do you have any idea of why all bumpers make fuse blow? If problem was only one i would have suspected some failure on solenoid board, but i this case i'm missing somenthing.
thank you for your help