Turn-a-round is often same day for “tune-up.” Includes cleaning, oil and greasing and replacing the common parts, which I stock for most clippers.
Clippers should be completely serviced every 6-12 months or when problems develop. You should do cleaning of accumulated hair daily.
I service Andis, Oster, Laube, Wahl, Lister. Note that not all models of clippers have parts available. Some brands are made in China and parts are often not available. New models usually don't have parts released by manufacture until they become out of warranty or make it in the market place.
Clippers under warranty should be returned to the manufacturer's service centers in most cases.
Supply chain issues have made getting parts very iffy. This should resolve over time.