what to replace?

[silk186]

I recently purchased a third hand GT Avalanche 1.0, I noticed the teeth in the crank were pretty worn so the seller took £30 off the price. I figured this is fair as that should be enough to cover replacement parts. I don't know the the specific bike model or age but it says it's a Shimano Deore FC-M442 crankset.

I have two choices:
a) clean it up, tune it and sell it for a profit - with the profits buy a similar bike in better condition.
b) clean it up, tune it and put a bit of money into it and keep it for 3 years until I leave the country.

The bike is said to have been sitting in a garage for a year. After washing and tuning it up I will see how it rides.
If everything else on it works well, what would be the best course concerning the crank. Riding it home the chain slipped several times. This could in part be due to the gears needing work but I did notice a lot of wear on the teeth. Is it advised to replace the whole crank or just the chain rings. In addition, I'm assuming that it is not necessary for it to be an FC-M442. If that's the case, how do I know what is compatible?

 

[silk186]

are chainrings from the 590 compatible like these?
This bike is just for commuting, lots of bad roads, potholes and construction.

 

[mrandmrspoves]

Give it a good clean and lube and see if the chain slip still occurs. If it does, you will need a new crank (chain rings at least!) a new chain and a new rear cassette. If the slipping is cured, I would carry on riding it until it starts slipping again. As far as the crank is concerned, as long as you have the same type (eg Square taper) and a similar number of teeth on each chain ring it should be fine