Do not have it fixed! They are very easy to fix. I have posted on several occasions, maybe not on hear but elsewhere about my experiences with the onan truck camper generator. First and foremost they have two problems that are common.
1, clean out the 02 exhaust hose that comes off the back of the diaphram. This is where the 02 is separated from the LP gas. If this is clogged it will take forever to start and will run like ****. If it takes forever to start and runs like **** this is whats wrong with it. The clog may go as far back as the fitting itself. Do this first!!!!!! DO NOT!! REPEAT!! DO NOT BLOW THIS LINE OUT WITH AIR!!!! YOU WILL CREATE PROBLEM #2. Remove this line and then blow it out.
2, the other common problem with these units is a blown baffle.
I will try to include some picks of the job I did.Of course the bad thing is your going to have to take the unit out and that's a biggy.

This is the adjustment screw for the baffle. It is not adjustable on my unit but may be on yours. The 02 exhaust hose comes out the other side of this baffle.

Unfortunately you'll have to drop the unit.

Here is the adjustment screw from the top.

This is the 02 exhaust hose that needs to be cleaned. Take it off and blow it out. I also had another problem. My baffle was busted.
You have to take the regulator off, take it apart and this is what you'll find.

A blown baffle.
I have many other pics as well as the contact info I used for ordering parts off the web if your interested. When I started this job I was thinking the same as you, get rid of it. Did some investigating and was able to fix it for about 200 bucks. Good luck sir.