If someone has replaced the 6BK4 and the 3A3/3AT2, etc. with one of the improved versions, radiation chances were less.
When I had my shop, the biggest failures were sweep tubes, and high voltage rectifiers, and regulators. I always checked HV levels, but rarely found them high.
Had an RCA CTC-38 that would come in every 2 years or so. It was run all day long in a hotel lobby. I replaced the 3A3, and the 6BK4, and set the HV. Once I found the HV running at 28K. The hotel said it was sizzling, and the pic would dim out on bright scenes, make a spark sound, and come back on. The 6BK4 resistor (dont remember the value) was burned open, The 6BK4 was shorted. I stopped buying LINDAL tubes about that time.
Went back to RCA's leaded glass 6BK4C. I dont recall ever having to replace one of them again.