Round CRT arcing problem

[Chad Hauris]

This weekend I got a Wards Airline round color TV at an estate sale, $5. It is an RCA CTC-15 clone. After I got the chassis operating, I noticed the CRT filaments were not lit and the CRT was arcing in the neck. I replaced the CRT with a 21FJP22 from another set, and the filaments lit up, but this time there is arcing from the CRT bulb to the mounting bracket. I replaced the HV anode lead, the 6BK4 plate lead, the 6BK4 tube, checked the 6BK4 cathode current to make sure the regulator is operating, and made sure the CRT was grounded to the chassis by alligator clips to the ground spring and also aluminum foil taped to the outside of the CRT. It is still arcing, though. Any ideas? Also, do you think the original CRT was destroyed by arcing (since it was arcing in the tube neck and filaments were dead). I can not find any evidence of cracks in the old tube.