If the lien and documents filed to obtain the lien were filed incorrectly, then a lawyer may be able to invalidate the lien - but the cheaper option is just to pay it, get the lien removed, and move on.

Will they go after the previous home owner who did not disclose (on seller's disclosure) that the tank was installed incorrectly (they must have known because they were the owners during the installation)?  

I BELIEVE it can be a win-win, but if approached incorrectly it can very easily come off as "Hey, you're out there hustling and I just want to ride your coattails".Any input is greatly appreciated.

I've also found that freelancers on these services don't really think long term and are more interested in getting the one task completed and paid for so they tend to cut corners and complete things in a way that will lead you to have to hire more people downstream to either fix issues that were done incorrectly before or redo previously completed work to accommodate a new scope that wasn't anticipated before.

Basically he wouldn't admit to any problems as fault including where his electrician removed existing vent fan I had already paid to install and damaged my cabinets, did terrible tile and drywall work, wired things incorrectly (to my spec), installed the doors improperly so they couldn't lock... etc etc.

Mods, have i posted incorrectly or in the wrong area to ask for such help?

Is this incorrect for what you are suggesting? 

The Bible has figs and an incorrect value for pi and the Roman Empire hard coded into it -- it may be a great place to draw wisdom from, but pi is still 3.14159(...) and not the number they have it as (also what the heck is a fig?).

In my case it was an incorrect roofing for low slopes that hadn't been stressed tested like this season.

If any experts can add to or even correct anything that is incorrect please chime in.