Any onan 6500 generator knowledge?

[38racing]

Someone dropped off a onan 6500 generator. Said fellow used it during our april ice storm but now won't run, puffs black smoke. It is electric start and recoil but battery is dead. It has a pull choke lever but seems to have other stuff attached to carb/choke. Has fuel shutoff solenoid on bottom. Without running choke isn't actually fully open when rod is in. I think maybe a coil expands with heat to fully open it. Using a booster I failed to start it. I shut fuel off to eliminate flooding. Since carb looks complicated I thought I change the sparkplug just on the remote chance that was issue. I drained carb bowl and only let it refill and again shut it off. So using booster I try starting including spraying carb cleaner into intake. Nothing really until all of a sudden it backfires out the carb and belches 5 seconds of black smoke and then runs like a top. Hertz and voltage right on. So after a few minutes I shut it down. I try restart and it does not fire. I pull choke lever and it's locked somehow,so can't close it. By this time booster is dead. Start working on something else and at some point I look down and see a clamp on the floor. Turns out to be a clamp holding screens on muffler output. Then I found the 2 little screens on the floor. They don't appear to be plugged though. At this point I found that I could pull the choke closed again. Anyway since booster was dead I haven't tried a restart. I downloaded both user and supposed service manuals. User simply says pull choke lever and slowly push back in as it starts. Service manual has nothing on choke system. I'll see what is does later today when I get back home.

[38racing]

So I just started it and it ran fine. Shutoff and same thing. Won't start with choke open but again I can't close choke with pull rod. There's a vacuum? hose on a pot on a bracket near choke. I pulled it off and choke went 3/4 closed and now I could pull closed with the rod.
Update: ran again. After shutoff choke locked again. Just let it sit for 20 minutes or so and choke now movable.

[KE4AVB]

I see if I have a service manual if you can post the model number. I got a handful of the generator manuals but very limited experience as I haven't seen one since 2014.

[38racing]

5EGMBE-5270

[KE4AVB]

I don't have that manual but here is link to a site where you buy the manual reasonably.

https://www.servicemanualbit.com/downloads/cummins-onan-5500-4egmbd-5269-6500-5egmbe-5270-generator-service-repair-manual/