Carefully flip the mainboard up to the right.

The board WILL catch on the bottom left corner, so be careful.

Side note: another common problem is having one of the mirrors fall out of place due to heat. It may be a good idea at this step to remove the cover of the mirror housing and check for this problem. If one of them has fallen off, use two-part epoxy to put it back in place, making sure to keep it pressed firmly and evenly against its seat.