generator usage

I am not a specialist in Onan generators but they do recommend that their generators be run on half load for 2 hours every month which is at least 300 hours for your rig. If you do not have the Owners manual for your you can download it from winnebagoind.com. The Onan manual can also be downloaded but from a Google search or from Onan.
These are things you should have in you rig.

My 2005 Onan only had 50 hours on it when I bought the RV this summer. I was concerned, however it started up and ran fine. I've put quite a few hours on it since then and it seems fine. I know the obvious of rotted lines and clogged carbs, are there other issues with low hours?

67.9 hours is not much time for a 2005 (assuming it's the original generator). I run my generator every 4-6 weeks under a load.
Some may disagree about excercising a generator. I think it's a good idea.

FOUND IT !!! It was inside on the wall where the power & tank level panels are. We are pleasantly surprised to find that this generator has just 67.9 hours running time. We just did a full service maintenance on it, and it's purring like a little kitten. Thank you folks.

Most of the Onan installations I've seen have a rocker switch on a panel inside that starts and stops the generator. Usually, right beside the switch is an hour meter. The meter only displays the hours if the generator is running. Otherwise it's blank.

Check the vent over the stove. Should also be another stop/start switch there for the generator.

Not familiar with your particular motorhome, but the generator hour meter is usually mounted on the dash of the motorhome.