Lenovo Thinkpad X61s throws a Fan Error

I replaced the CPU heatsink/fan assembly. I put grease on both dies without making contact with bare skin. I believe I put an appropriate amount of torque on the three screws on the CPU and the sole screw on the GPU. I'm using the 9-cell battery without the plastic extender piece.

I can hear the fan in motion by putting my ear to the vent hole. This laptop has only one fan. Some laptops have a second fan towards the latch, but this is not one of them.

I'm getting a Fan Error. This didn't happen with the original fan.

I believe the replacement fan is OEM. A decal indicates it was made by Toshiba.

I got another heatsink/fan. Looks similar to the first replacement. I ripped the pink, thermal pad on the GPU and discarded that.

I got the same Fan Error

Both fans looks like they are free from dust.

I may just try to clean the original part and use that, instead. Not even sure if that's possible, since the fan's magnetically driven.

I'm going to focus on the motherboard, but not sure what to look for except dust bunnies (original heatsink/fan was clogged/dirty).

Other thoughts and ideas are welcome.