You can do the basic convergance, there is a convergence that you do not have access to, when I had my TV go wonky, someone came out to look at it (repair man) and he got into some weird menu, and the convergence screen there was none I have seen when setting up my own TV. The TV has a small grid where you could align almost every inch. So I did some research on it and found out there is definately a "hidden menu system" that allow for all sorts of tweaks. But the warning said if you did not know what you were doing to not go into this mode ,as it was not a straight forward menu, that you selected.
Also check out
http://myweb.accessus.net/~090/how2adj.html#1.2 it even mentions that a Rear Projection needs to be tuned. Let me quota a couple sections fromthe above site.
Calibration is for the most part directed at the Home Theater enthusiasts who want to get the full potential that their television sets can offer. It also has the possibility of adding a 3-dimensional realism and a "film like" look to video. When done properly it has the potential to extending the life of rear projectors (R/P's) by limiting and lowering the average light level output.
FYI - Most non-calibrated R/P's loose somewhere between 25-30% of their total light output in the first 1000 hours of use. After the first 1000 hours, light output remains almost consistent throughout the remaining life of the picture tubes (about +/- 10,000 hours).
1.3 WHAT TELEVISIONS NEED CALIBRATION
Currently no manufactured television (Direct View or Projection) out-of-the-box offers true NTSC gray scale tracking. Most TV's suffer from overscan, SVM, etc. Calibration can bring most TV's closer to the true NTSC standard.
1.3a REAR PROJECTORS (R/P's)
Rear projectors (R/P's) need proper initial setup and calibration if they are to give the degree of focus and clarity comparable to that of a Direct View (tube) set. In general R/P's, geometry, though improved, still needs work. Even with the best possible efforts with the "French horn screws" or s/w equivalent, it is impossible to get the "roller coaster" effect out of the ticker crawls. Also, convergence drift is still a problem. The price of that tremendous light output continues to be more than average viewing hotspots