Seems to surge in power when under a small load, after replacing gears

My girlfriend's Pro 600 had started skipping gears it sounded like and after viewing a couple troubleshooting videos it seemed like we needed to replace a stripped gear or gears. When I opened it up there weren't any obvious damages but it did look like there was some wear on a few gears. We ordered and replaced basically all new gears from the motor to the planetary ring gear.

I installed all the parts as shown in the blown up picture of the mixer. Applied tons of fresh grease to everything, after detail cleaning all the old grease before replacing the parts. With no load it runs smoothly and sounds fine except a light knocking.

She tried her first cake mix in it and shortly after it started it would sound like it surged in power up and down. She was able to finish the batter but we're not looking to use it again until we can fix this problem.

Also, the video we watched showed the bushings installed with the flat sides perpendicular to the counter top but the blow up picture shows them parallel. I installed them the way the video showed but it does appear they could go either way.

Thanks for any help!