older tin drop flue sap pan leaking

[das fisch]

I have an older 2'x4' drop flue divided pan which I'd like to get back in working order. there are a few pinholes on the bottom of three out of six drop flues (which measure about 3/4" wide by 12" long). it's hard to get an iron down into the flues to solder from the inside so I can either solder from the bottom (fire side) or one of the following quirky ideas;
-trim off bottom faces and reface with new copper. basically make troughs the same shape as flues maybe 1/2" deep and solder onto bottom to cap off
-apply a skim coat of solder to inside of flue's. basically smelt down some silver solder and drop in from the top/inside of the flues. essentially pouring a new bottom.

Yes, I'd love to buy a new unit, but I do not have that kind of cash at this point and I do not sell the product, so I'm looking for alternatives.

[mapleack]

Solder the pinholes from the bottom. Clean the areas well with a wire brush, then use liquid flux made for tin to clean them. Use copper or bronze irons you heat with a torch. A little finess and good luck and you'll be back in business.