Its rather obvious that there is a bad connection or dry joint on some of the circuit board connections / components, something which unfortunately cannot be rectified at a distance as it requires methodical fault finding. I suggest that with the cabinet undone and the TV powered up, carefully prod various areas with the use of a "PLASTIC" rod, (knitting needle or similar) as that is liable to locate the defective area, do "NOT" touch anywhere near the connector on the side of the tube (or red wire to) as there can be approx 20,000 volts on this whether or not the screen is blank. ONLY try this if you are electrically inclined, if you aren't do not attempt it!