Maintaining Your Skateboard
Skateboards do need minimal maintenance. Nuts and bolts can jiggle loose. Parts wear out beyond safety standards. You need to take care of your skateboard and make sure it is operating properly in order to avoid any needless injuries. Spend five minutes making sure your skateboard is ready to session -- or five months in a cast because you didn't bother checking you board, and you didn't notice that your wheel was about to fall off. Yikes!
Decks
Skateboards are mostly made from wood ply pressed together and glued. Even the best-built boards can have problems from the demanding pressures that riding a skateboard can do it. I have seen skateboards manufactured from other types of durable materials, but nothing has compared to the ride of a good maple deck. If you ride a lot your board is going to wear out and need replacing. Visible pressure cracks are not uncommon, but if your board is cracked badly through multiple ply or has separated between the plys, it's time for a new one. The bottom line is, because of the nature of skateboarding, boards take a lot of abuse and they do wear out. Don't risk the chance of broken bones!
Grip Tape
You can clean excessively dirty grip tape with a plastic bristle brush and some water. Unfortunately, grip tape is almost impossible to remove from a skateboard, so it really cannot be replaced. Don't go crazy with the water. Towel off excess, and leave in the sun to dry.
Truck Mounting Hardware
Truck mounting hardware (holds trucks to the skateboard deck) can get loose from all the vibrations and banging around that a skateboard goes through. Make sure the hardware is tight and secure.
Trucks
If the rubber bushings -- or pivot cups -- are all smooshed and out of whack, it is time to replace them. Almost all truck manufacturers sell replacement parts, and there are some third party companies that also sell parts. Replacing bushings and pivots can make your old trucks ride like new. Just remove the kingpin tension nut, work the old cushions off, replace the metal retainer cups if needed (they get smashed), and put the new cushions on. Inspect the actual truck hangers and base plates for any cracks. Replace when necessary.
Axle Wheel Lock Nuts
These hold your wheels onto the trucks. Always check these before going skateboarding. Also, check them often during your sessions (not to mention the rest of your board). Axle nuts tend to wear out and loosen with repeated tightening and removal. Replace them even if there is a slight doubt of their condition. There is nothing worse than setting for a big rail, when suddenly, you see this wheel zooming out if front of you. Whammo! No good.
Wheels
Wheels should be smooth and free of any major irregularities or damage. Large chunks of missing urethane, flat spots, or just long time wear should be replaced. If any of your bearings seem to pop out too easily, the wheel-bearing seat may be damaged, and justifies replacement.
Bearings
Bearings are the little metal components that allow the wheels on your skateboard to spin. You will know if your bearings are in need of service. They won't spin freely anymore. If they make a little noise or are a little rough you may need to clean them. Some bearings are not made to take apart and clean. You should replace these with freshies. It might be best to opt for ones that you can service. If you do have serviceable bearings, you will be removing them from the wheel, popping off the shields, spraying them out with solvent, adding lubricant and putting them back together. Follow bearing manufacturer directions for best results. Warning: this can be a tedious and nerve racking job.
Remember, you don't want to waste any quality skateboard riding time on some stupid injury because your skateboard was neglected. Take care of your skateboard and it will take care of you.