That sounds pretty far out of tram to me - I would recommend retramming your machine if you have the time. I posted about going through this process a few months ago. It's not terribly hard to accomplish, but it is fairly involved overall. If you have an engine hoist, an additional bottle or scissor jack, and some brass shim stock, you've got all you need to retram your 1100. I used a 4"x12" cylinder square with a spindle-mounted test indicator reading off the X and Y axis deviations as the column traversed in Z in order to perform my tram measurements, but a swinging test indicator like you used is sufficient too. I'd recommend a larger swing than 1.5" for greater sensitivity though. When I finished the process (it took me two tries to get it right) I found that my surface finishes actually improved from when the machine was new. Given that I had a serious finish problem when I started, it was certainly worth it, but if I had even a somewhat questionable surface finish I'd still say it would be worth going through the hassle of tramming your column.