RE: first hobby/nitro rc
I would recommend getting an instruction manual for it, and COMPLETELY stripping it down to parts, clean all the parts, and replace anything that looks beyond repair, check all bearings. Take off the backplate of the engine, by removing the pullstart, then taking off the backplate, what you are looking for is RUST on the crankshaft or bearings. If there is rust on the crank, you will need to replace it. If the bearings are rusted, they are toast too. For the rebuild you can get away with leaving the engine on the chassis....
Once you have cleaned and rebuilt, you will have a near-new car! You won't regret doing a rebuild!
A side note on the O.S. CV-x engines. These engines are great, reliable, tough as old boots, easy to tune and they hold a tune well! The power output is great for the price of the engine.