I assume that the lien was placed in accordance with Sec 37 of 770 ILCS 60/37, which reads:
"Sec. 37. Any architect, contractor, sub-contractor, materialman, or other person furnishing services, labor or material for the purpose of or in constructing, building, altering, repairing or ornamenting a boat, barge or other water craft or mobile home, shall have a lien on such boat, barge or other water craft or mobile home for the value of such services, labor or material in the same manner as in this act provided for services, labor or material furnished by such parties for the purpose of building, altering, repairing or ornamenting a house or other building. And such lien may be established and enforced in the same manner as liens are established and enforced under this act, and the
parties shall be held to the same obligations, duties and liabilities as in case of a contract for building, altering, repairing or ornamenting a house or other building.
(Source: P.A. 82-535.)"
The full statute can be found at:
http://www.legis.state.il.us/ilcs/ch770/ch770act60.htm
Trying to challenge an in-place lien is not a simple manner, but it sounds to me like you need to challenge its validity.
I suggest that you contact an Illinois attorney familiar with your laws. You can find one by contacting your local State Bar Association office and asking for a Lawyer Referral to someone familiar with Illinois Mechanic Lien Law.
A websearch also found the following firms that have online information on the subject:
http://www.fandh.com/practice/realestate/realestateqa.html
http://www.obrienlawoffices.com/casestudies6.html
http://www.hcmllp.com/artJRK5.htm <== INTERESTING!!!
Hope this helps..... And keep us apprised of the status!