Ther are two questions of fact here:
1. Whose fault is the missing pigtail? Did you remove it thinking it was
junk? If so, you are at fault and would have to pay for it.
2. How long was a "reasonable period" for them to remove the tank. And,
related, when did you first ask them to remove the tank. If they waited
an unreasonably long time, then any damage(*) is their fault for not
removing the tank within a reasonable amount of time.
If it were me, I guess I'd offer to settle for $25 or 50. That way they
get something for the missing part. If they go to court, they'll have to
pay a filing fee (usually around $50) and pay somebody to serve you with
the papers (another $50-150). And they might lose in court, so then
they'd have paid $100 or more, plus spent time in court, and end up with
nothing.
Also, the $100 they're asking for is probably the price of a new
pigtail. But the pigtail wasn't new: it had been sitting out -- probably
exposed to weather etc. -- for (by your description) at least 2-1/2
years. SO there's "depreciation".
And of course, if they sue, you'll have to appear, which will mean time
away from work or whatever you do during the day, so you also have a
reason to pay something to make it go away. And if they win, you'll also
have to pay for the cost of filing the lawsuit and serving the papers.
I'd make the offer in writing, and keep a copy of the letter. If it goes
to court and and they are awarded less than you offered (you can enter
your copy of the letter into evidence), then you don't have to pay the
filing fee and cost of serving the papers.
So both sides have an incentive to "settle out of court". Which is the
way it should be -- a lawsuit should be a last resort.
NOTE: I am not a lawyer. I don't even play one on TV. But I might enjoy
playing Leland McKenzie of "LA Law". Crusty old guy who knows what he's
doing. (Arnie Becker would be fun, but I'm not tall enough or smooth
enough to play him.) I wouldn't want to play ANYBODY on "Suits" or "The
Practice" or "Boston Legal". Disgusting people.
(*) Assuming that you are not at fault in question 1.
--
I do so have a memory. It's backed up on DVD... somewhere...