I picked up a Gottlieb Target Alpha a couple months ago, it’s been a blast to play. I have a bonus scoring issue that occurs intermittently. The non scoring issue only occurs after the 1st ball drains for 1st player only, the bonus unit does not start, ball simply hits outhole and quickly shoots out for 2nd ball without the bonus unit ever kicking in. This occurs in approximately 1 out of every 10 games after only the first ball. The bonus unit works perfectly fine for all other balls. It’s been a MAJOR thorn in my side for weeks, everything in the circuit has been checked/adjusted/cleaned numerous times. It’s frustrating having a great 1st ball, hitting 10-15 targets without getting your bonus points afterwards. Any suggestions greatly appreciated.

UPDATE-NON-SCORING BONUS ISSUE RESOLVED!
Thank you to everyone for all your posts, greatly appreciated!! Sorry it's been a while since I posted. This non-scoring bonus issue has been a major headache. Everything that was suggested was looked at in great detail. After being frustrated repeatedly, I finally decided to throw a phone and light inside the coin door to record the bonus stepper while everyone was playing. Well, the non-scoring bonus issue occurred again and it was recorded. After watching the video, I noticed the bonus stepper did not reset properly when the start button was pressed again to add more players. I know the start button to add players will not function immediately after starting a game however the button to add players does function once the score reels have reset but that's still a second or two before the ball gets kicked out. It’s always been a habit (in this case, ended up being a bad habit) to wait for that certain sound then you know the start button will work to add other players. Once I knew the cause, I was actually able to duplicate this issue several more times. I determined this intermittent bonus issue only occurs when you add 2nd, 3rd or 4th players, the one player games work fine.

So basically, the problem appears if the motor is still running at the exact moment the ball rolls over that switch at the shooter lane, this switch resets the bonus stepper. This is why it was intermittent and only occurring for 1st ball for first player only. Crazy how it ended up being something so simple. We now wait until the ball is in the shooter lane to add players.

UPDATE-NON-SCORING BONUS ISSUE RESOLVED!
Thank you to everyone for all your posts, greatly appreciated!! Sorry it's been a while since I posted. This non-scoring bonus issue has been a major headache. Everything that was suggested was looked at in great detail. After being frustrated repeatedly, I finally decided to throw a phone and light inside the coin door to record the bonus stepper while everyone was playing. Well, the non-scoring bonus issue occurred again and it was recorded. After watching the video, I noticed the bonus stepper did not reset properly when the start button was pressed again to add more players. I know the start button to add players will not function immediately after starting a game however the button to add players does function once the score reels have reset but that's still a second or two before the ball gets kicked out. It’s always been a habit (in this case, ended up being a bad habit) to wait for that certain sound then you know the start button will work to add other players. Once I knew the cause, I was actually able to duplicate this issue several more times. I determined this intermittent bonus issue only occurs when you add 2nd, 3rd or 4th players, the one player games work fine.

So basically, the problem appears if the motor is still running at the exact moment the ball rolls over that switch at the shooter lane, this switch resets the bonus stepper. This is why it was intermittent and only occurring for 1st ball for first player only. Crazy how it ended up being something so simple. We now wait until the ball is in the shooter lane to add players.