Preventive maintenance or wait till it breaks?

Maintenance requirements vary according to environmental factors. Cigarette smoke is one of the worst fiends. That, along with high humidity and airborne dust create a layer of foul-smelling crud on everything. This wreaks havoc with convective cooling and throws finely tuned circuits out of tolerance. Every vintage piece of equipment I buy gets torn down, vacuumed, dusted with a small artist’s brush and cleaned of any flux residue etc... after that things look better, smell better and work better and longer. 

Beware most “computer” type fans are garbage. The giveaway tell-tale signs? - if a fan has LEDs in it for “gee-whiz” factor, it’s garbage. If a fan is sold under any second-rate computer brand (Assus, Assrock, Gigabyte, etc.. ) it’s junk. Just go for the plain-Jane fans from Sunon or others. Otherwise, you will spend twice as much as you should, on a fan that might last a few months at best.