metallic taste in the output

[redridinghood]

So I have done this, successfully, a number of times over the years -- same equipment, same mash recipe. My last couple of runs were absolutely horrible, taste wise. The spirit has a metallic tang to it, like some chemical reaction. There is also a bit of bitterness to it. All and all, its not drinkable. Any ideas? Its all stainless steel, with a copper mesh that goes into the column. Does copper ever get scratched up and old? Heating elements got old and smelly? Not that I can get to them in any case......
Well, thanks a lot for any suggestions.

Forgot to mention -- its electric, with 2 heating elements

[NZChris]

What you put in it might have something to do with it, but you didn't say.

[Deerhunter]

Try doing a cleaning run.

[rad14701]

Heating elements can get a buildup of burnt crust on them... The copper scrubbers could either not be 100% copper or have deteriorated over time by doing their job...