Preferred method for soldering old/corrded leads

[somnif]

So, I'm looking for opinions here. I spent an afternoon catching up on some projects, and one bit involved some rather pricey NOS diodes. Annoyingly, I just could not get the damn leads to wet with solder. I didn't want to spent too much time on them with the iron, as well, at a buck a piece I don't want to toast my germanium, so I ended up with a rather messy job (clipping the leads and wetting the freshly exposed spot of metal on the end).

My usual trick with older components is the judicious application of rosin flux. Its messy and smokey and it tends to cut through crap just fine. But these diodes just refused.

If I had thought about it before starting I probably would have tried sanding the leads a bit to see if it would help, but hindsight etc.

Anyone else have any experience/advice/horror stories to share?