Safety Inspections
Check springs, extension and or torsion to see if they are worn
and in need of replacement
Check rollers to see if they are worn out
Check cables and pulleys to make sure they are not damaged  
Tighten all nuts and bolts and lube/spray the door

Repairs
Replace broken springs: torsion or extension
Replace rollers, cables, and pulleys
Repairs to some door openers, transmitters, and additional
components available