LARRY DILLON HELP-old Mitsubishi projection TV :TS-5545 audio bat no Picture

 I have a mitsubishi projection TV  modell: TS-5545 .  from 1996 year.   From time to time on my tv, the screen stops working but you can hear sound (and now it lost picture completely bat have sound).  The tv has had this problem for a long time for sort times.  Someone told me it might be cold soldiering.  I have taken apart the entire tv, and have checked the entire main circiut board, and each separate board on each light.  I tried poking around diffirent parts w/ a wooden stick to check bad contacts.   I re soldiered around 30 percent of the circiut points.  There are no burns or anything everything seems fine.After it has completely lost picture, what can i do to repair my problem?