I'd talk to your TV repair person why they are replacing the entire engine.
I have a sony wega KDF-E50A10 for almost 3 years now (buyed used) and everything fine until last couple month. The screen begin to take gradually a yellowish tint and now she have a couple of blue spot everywhere in it. I check on the web and i found that it's certainy the optical block engine and it's almost 800$!! Do i have another way to resolve this problem that seem to be a ''design flaw''?