1100MP Problems

This is the third 1100MP project that Dell has sent me, because the first two had defects.  The warranty has expired and now am looking for help.   The repair facilities that dell referred me to do not repair the 1100 nor the 1800.   The lamp will come on at times and not come on at times.   There is no pattern to when it will work.   I've taken it to a engineer who tells me the ballast is causing the problem.   Where can I get a ballast???    It is very disappointing to spend $650 for a Dell project that has given me so many problems.  

chris