Acquired a Snapper 21401PS

Just came into possession of a running in decent shape push mower. I had to get into the carb some and clean it up but it runs for now. It needs some new belts ( looking for part #'s ) and need to know if the throttle on this mower is correct. Got the electric start working with a battery I had laying around in the garage but the bracket isn't factory. It winds over slow but with the throttle in the start position is takes a couple of times to get the old girl fired up. Pull start works great... Must keep the throttle all the way forward in the start position for some time ( 2 mins ) before I can let it back otherwise it dies. Here's my question... Is the throttle on this thing variable in speed meaning is it suppose to slowly wind down as the throttle position goes back towards the off position? Mine pretty much stays max throttle until it hits the stop position, so no slow idle and not sure if this is normal or not...
Here's some info on the unit..

Snapper 4 hp Hi Vac
Model 21401PS
Serial # 64244222

On the B&S engine
Model 110907
Type 3913-01
Code 86032404

I believe it's a 1986 model, 11 cubic in, Vertical, Pulsa-jet, electric start, gear drive, with alternator.

Can anyone confirm my info and shed some light on the situation...

Here's some pics...

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Image may be NSFW.
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Image may be NSFW.
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Mike