Refrig & freezer not cold enough; ice forming;...

Question

Coils very dirty. Just cleaned. Evap motor replaced a year or two ago; symptoms above are exactly like when we replaced the evap motor.

Air is circulating in refrig and freezer but much less volume and not cold enough to freeze.

1. Could I have lost another evap motor?
2. How do I check the evap motor?

I am mechanically inclined and can follow directions. Need to save money. Where do I go to find step by step to R & R evap motor?