Newbie rebuilding an old still. Best way to resolder?

[Momma'sMistake]

I've run a 25L pot still with a 2" whiskey column for several months and have pretty well figured it out. I decided I wanted to go on to bigger and better things so I went gear hunting. An old friend steered me to the widow of an old shiner and more out of compassion than common sense, I bought his old 60L with a 32 inch x 2" column. It has a 30L thumper and a 24 inch X 2 inch dia over 3/4 inch shotgun condenser plus a 12 foot 1/2 inch worm. Pretty classic for this part of the country. My problem is that when I fired it up to clean it, I discovered several leaks in the 2 inch column. I've built a column from scratch and had no problem mapp soldering all the joints but with this older column I can't get a consistent flow and keep getting gaps. I'm using H2O based flux in the gaps but feel that's of no effect. Do I need to bite the bullet and tear it down or is there some way to get these joints right?

[Fil]

Im no expert, far from it, and all my experience is with well fitting modern end feed couplings, so im not writing with any authority on the subject...

Reading the post tho a few things spring to mind.

how old is it?? is it possible its made with lead content solder?? if so stripping down cleaning off and re tinning with lead free solder could be well worthwhile. a lead testing kit may be worth the investment?

Secondly if its a soft tin solder MAPP gas may be heating too hot too quick, giving you a short window of opportunity at the working temp for your solder? perhaps cooler propane would work out better?

Also as its old joints that leak, any exposed copper in the leak area isnt going to be clean and bright which is what the water based fluxes work best with, perhaps using a more aggressive liquid acid flux used with harder silver content solder may eat the surface crud off and allow the solder to take?

It would be interesting to see some pics of the monster..

[Boozoid]

In my experiance you want to heat the copper just upto the point the solderflows.
By carefully controlling the heat I've soldered lead sheets. MAP gas is probably too fierce for soldering such a large lump, so keep the torch moving quickly all over.

Lots of solders have slightly diff melting temps so If you keep having issues it may make sense to clean off the old and start again with fresh.

[Anavrin]

Have you got any pics of this contraption, it would be nice to see what it looks like :-)

[Momma'sMistake]

Thanks for the informative replies. I had already tested it for lead and was good there. Today I bought a wide flame LP tip and it did the job. Evidently I was boiling the solder right out of the joint due to the high heat produced by the Mapp torch. Thanks for the suggestion there. The thumper is a 20.9 liter aluminum Mirro pressure cooker made in 1986. It has 3/4 inch cooper in and out with a circular vapor coil that's held off the bottom with stainless steel bolts. I was curious if the aluminum was a bad choice for a thumper vessel as well as the rubber seal? It looks like it's seen quite a few runs and shows no copper oxide build up but I was worried about what flavor the aluminum may impart. My first steel was an aluminum turkey cooker pan and I could taste it . I was hoping that was caused by the acidity in the wash and thinking that won't be present in the thumper. I can replace the rubber gasket with cotton rope if you all think it may be a problem. I plan on running with the condenser instead of the worm so I'll have better temp control but the old worm in it's blue porcelain container sure brings back memories of the small "paint maker" my grandpa had in the shed. As far as photos, I'm in an area where what I'm talking about is illegal to posses so I'm paranoid about documenting any alleged ownership of it. Thanks again for soldering advice.