RCT1 Ride Crashes

Two questions here:

1. It always seems that my rides crash after a few years even when i have the mechanics checking on them every 10 minutes. is this just something with crappy mechanics or is it just how the game is set up? btw most of the rides are prefabricated ones if that makes a difference.

2. what do i do with the ride once it's crashed? is there a way to get it back up and running b/c the only thing that seems to work is to demolish it and rebuild.

Any feedback is more than welcome!! thx