Do you know for sure that it is a sit down? A "queen quilter" sounds like the longarm with an 8 or 10' frame that was built for Sewing Machines Plus to sell as their offering (and looked identical to Tin Lizzie; quite possibly built for their rebranding), much as their "King Quilter". The Tin Lizzie-branded sit down was, I believe, called the Apprentice. I believe sit down and frame 18" machines are the same basic machine, but a longarm with frame will not have a foot pedal and a sitdown machine would require wheels and encoders to put on a frame (and stitch regulator).
Tin Lizzie is no more. There is a new company called Locksmith Lizzie that has machines which look similar (and may, in fact, be mostly the same), but they do not support the old Tin Lizzie models. This according to the owner of a longarm retailer who has taken them in on trade and has problems sourcing some parts so he can resell them.
Still, never look a gift longarm or midarm in the needle bar ;-) I would start searching for info by looking for a Facebook group and also perhaps contacting Sewing Machines Plus if you determine it was one of their machines.
Last edited by mkc; 08-31-2020 at 01:31 PM.