What's this lamp, AGM or not ?

Soak the whole thing in acetone for a week. Dry it, apply moderate heat, then treat the affected area with penetrating oil for a few days.

Tony

 

The dip tube or fuel pickup tube is supposed to be screwed and attached to the valve block(which you've already removed), not to the fount.
Is the dip tube completely seized?
I guess you'll have to eventually remove the paint on the fount if you planned to weld or braze it up.
First fill, soak and clean it with some organic solvents such as acetone as Tony suggested.
If it still wouldn't budge, try some alkaline degreasing liquids (do not apply on the aluminium generator) such as caustic soda to remove any aged, caked up, varnished or hardened perhaps 'polymerized' fuel deposits. Then rinse with clean water. Check if the fuel pickup is then freed.
Otherwise, followed by citric acid soak to remove all internal rusting. Its all steel and brass. It could take up to two days to completely soften every speck of rust. This could also be holding the fuel pick-up tube in the fount. As you do this, additional pin holes may show up as the rust is cleared. These could be too many to practically patch(depends). You'll need to to check the integrity and condition of the fount to see if it has not thinned out too much from the rusting. Then you could decide if its still safe for use.

 

Thanks guys !!!
Work for the coming days

 

Good luck. That's going to be a tough one I guess. Especially the fount repairs. Remember to dry it up quickly if you ever rinse with water and apply some flash-rust preventive measures.

 

I would need it

 

The whole thing should come out of the tank. Appears the fuel/air part of the tube is still lodged/ stuck in the tank. It's more than likely not a salvagable item at this point.
As far as I know no Coleman generator was ever designed to be cleaned; they are a throw away item. You could clean the tip on the Q77 and Q99 type generators. I'm not saying if work like hell at it you can't clean a Coleman generator but they were not ment to be fittled. Only people like us do that!

 

Exactly as @george mentioned about the milspec generator. Its next to crazy trying to clean that. Its meant to be a disposable item.
Anyway, I've done that mainly because there's no way for me to obtain a replacement. Straightened the aluminium tube a little, removed all the asbestos string/mesh inside, flush clean with solvents, replaced the mesh with metal braiding, bent it back to shape, cleaned the jet nipple, re-assembled it and re-use.

 

@MYN good idea replacing asbestos by metal braiding, i keep it

 

@Sellig33
The reason I used metal braiding instead of asbestos was:-
1. Its stronger and less likely to release tiny particles that could clog the generator.
2. It conducts heat from the generator tube wall to the fuel better and more uniformly throughout, which I believe would also reduce pulsing due any form of 'Leidenfrost' effect.

None of them is related to any avoidance of the hazards concerning asbestos here.