I sew a lot so over the years I have taken my machines in yearly for a tune up. I have a 1977 Viking that is still going strong and has been passed on to my daughter. That is a mechanical machine. I have my newer computerized machines also serviced every 12-18 months with me cleaning in between. I service my Featherweights myself.
I think it is important to take care of expensive equipment, just like I do my car.