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B+ is dangerous but it usually dissapates within a minute or two of unplugging the set. HV to the CRT is around 20KV with usually less than 1mA max...A static shock from shuffling on carpet and touching a door knob can be as much as 35KV and similar current/charge.... I've taken both multiple times and am fine...the worst part is what your reflexes cause you to smash into. If you take care to work with the set off and short any Electrolytic capacitors and the CRT HV line (place a 1M resistor in series to prevent dielectric charge bounce back) to ground you won't get zapped.
When working with the set powered avoid touching wires.connected to the flyback, yoke, and HV, work with one hand in your pocket and rubber soled shoes and avoid touching grounded objects with anything but your one hand not in your pocket. Voltage is not dangerous (though higher voltage facilitates current flow) current is dangerous 30mA=0.03A across your chest is enough to kill.... avoid current flow through your chest. AC is more dangerous than DC...DC will reset heart beat when you touch it but you will continue to move and have a heart beat while holding it assuming non leathal current flow. AC will will prevent your heart and muscles from functioning normally...the transformer, if it uses a power transformer,or power cord end B+ rectifier and anything connected to the power cord (series string tubes?) Is the most dangerous area.
Most servicing especially the recap can be done with the set powered off...
Just to be clear a tube lighting does not mean it is good... just that it is not dead in an obvious way. A tube can light but have no cathode emission or have inter-element shorts that make it non-functional in circuit. You should test your tubes in a purpose built emission or better yet mutual conductance type tube tester (they made cheap heater only tube testers but those are as unreliable as eyeballing for heater glow).
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