I'm looking for ideas! A while ago I bought a plastic kit, described as "started". What they actually meant was "some bits have been thrown together and Araldite chucked at it in the hope that the bits will magically line up"!
So, does anyone have any ideas on anything that I can dunk these bits in and watch the Araldite (or whatever epoxy it is) float away? I haven't had much luck searching on Google. My favoured method in these circumstances won't exactly work on plastic - Nitromors :-)
You could try chucking the offending items into the freezer, some epoxy's will weaken with cold (although some need heating in an oven, not an option in your case...), otherwise I suspect that you might have to put this one down to experience! :~(
If that is anything like what I think it is , similar to the nitric acid that can be found in some types of decaying (over heated) rubber, it is NOT to be used without appropriate safety instruction and certainly not without full body (inc. face / head) protection.
 can cause irreversible and spreading damage to the bone structure, IIRC it dissolves calcium, the only cure AIUI is amputation above damaged bone....
A kit of what, though? Wrecked rolling stock kits can be finessed into "end of siding" withdrawn grot, or a scrapyard/fire-damage diorama - get some figures and a trolley, and have the scrapping crew in with crowbars and oxy cutter. Van bodies can be used as yard storage, with the worst of exterior or roof damage disguised by loads of weathering and making a tarpaulin from paint-stiffened tissue paper. Even a loco could be withdrawn awaiting scrapping, with a tarpaulin over the chimney and the rods in the tender. Buildings can be plundered for usable runs of brickwork, chimney, window frames, ridge tiles, etc., or sawn in slices to fill a backscene under trees.
There are proprietary superglue ungluing solvents which MIGHT work on two-part epoxy, and it's possible that acetone nail varnish remover may locally undo a few joints though possibly distorting the styrene too.
Otherwise, put the offending bits through the kitchen mincer and use the residue to make wagon loads! A useful tip I picked up from Expo EM a few years ago, was from a building modeller who put his bits of kit sprue and damaged parts, into a jar of the liquid poly jointing solvent/MEK - it turns into a slonk that can be applied with a cheap paintbrush to build up strengthening fillets inside joints (the dissolved styrene stops the solvent from atacking the wanted surface quite so drastically too), do flashing on rooves, fill ugly gaps and even make small ad-hoc castings in a rubber or metal mould - handy for making scrap chairs for the p-way yard, axle boxes, rotted planks, etc.
Go to Halfords and buy a tin of brake fluid. Despite a change in formulation it still seems to work on twin-pack quick-setting types. But try it on a bit of the plastic first! Takes quite a time to soften the resin.
I'm surprised that no one has mentioned the obvious answer. Put a new blade in your trusty modelling knife and pare the dried Araldite away. Yes, it's time consuming, but it won't dissolve the plastic.
Two points, make sure the plastic you try is the same type and surface area and thickness as the bits you are trying to save, secondly, brake fluid can take no time at all to soften the plastic.... There is then the problem of getting rid off all traces of the brake fluid before painting.