Here's how to keep your headstock running smoothly, whether it is brand new, or if I just tuned it up for you, or if you just did it yourself.
1. Keep it clean! Dust on the inside gives you lots of problems. Use source dust collectors and hopefully also an air handler type of dust collector. This will help your health as well as your machine's. Suck up the sawdust with your sawguard, when sanding or when finishing that pen you just turned. Sawdust gets easily sucked into the headstock and once there gets into the motor and blown all around, coating speed control parts, gunking up the bearings, etc. Sawdust can draw out the grease from your bearings, acting like a wick. It can also act as an insulator, making your motor run hotter and keeping all the bearings hotter. The moisture in the dust can rust parts, too. Later when the dust has dried, it can attract moisture from the air and start that cycle all over again. So, try to avoid allowing the dust to get in and on your headstock in the first place. If you can, periodically drop the motor pan and vacuum the dust out as best you can.
2. Keep it lubed! There are only two points really needing regular lubrication. The idler shaft/control sheave changes the speed as you turn the speed control handle. It needs a few drops of lightweight oil every 5 hours or running time, or every few months. The sheave on the motor's shaft needs the same. Most sheaves have a small hole for oiling purposes but if you don't have one or can't locate it, lube the shaft directly. A needle pointed oiler is easiest, or you can put some oil on a slender screwdriver and drop the oil in that way. 3 in 1 brand, sewing machine oil, turbine oil are ideas of the type of oil to use.
3. Use it! A machine that sits there unused can have more problems than a regularly used machine. The belts can get stuck in a certain position and from then on they'll have two lumps each robbing the machine of power and making more noise. Regular use also re-distributes oil and grease keeping parts lubed better and combating rust. Run it every once in a while during the off season to give it a little exercise, even if you are not doing any projects.
4. Investigate unusual noises and vibrations. If the machine changes noises, turn it off and figure out why. I have seen machines with the quadrants completely cut in half by a frozen control sheave bearing. The operator must have listened to horrendous metal on metal skreeching sounds for a long time for that to happen. Same thing with sparking or burning smells. Turn it off, unplug it and figure out what's up.
5. Be familiar with its layout. Look it over well so you can recognize when internal components are out of place. A protruding idler shaft can prematurely wear out belts, for instance. Wiring to the switch should be away from the worm shaft of the speed changer, etc.
6. Keep the upper belt tensioned properly. I recommend just enough tension on the poly v belt to prevent slippage. Too much tension stretches the belt and puts undue pressure on bearings. Adjust the tension if it ever slips but don't overdo it.