For the front end, check the spindles and shocks to make sure everything is light and greased.
For the engine bay, check for any leaks, worn or split wires, check the carb boots to make sure there are no cracks in them.
For the rear skid, check over all the bogey wheels to make sure they aren't cracked or chunked and turn freely. Make sure that the rear springs are seated properly and haven't worn through the plastic keepers. Then make sure that the entire rear skid is greased at all the points. Check track tension and alignment as well.
That should give you quite a bit to look at and hopefully if there are any other issues, you will spot them when you are going over each part of the sled.