Is rectification in fluorescent lamps are more dangerous to the ballast then welded (Stuck) glow starters?

Is rectification in fluorescent lamps are more dangerous to the ballast then welded (Stuck) glow starters?

Seems to depend on ballast. In the US, one type of destructive rectification I've seen are F14 and F15 size in trigger start (aka rapid start) normal power factor ballasts. It seems when the lamps fail, the lamp current increases due to current going in one direction through ballast coil instead of both, losing the counter EMF that limits the current. The other type is the instant start tulamp ballasts for F48 and F96 sizes. In this case, when the lamp on the blue wire side fails, the power factor of the ballast falls causing the primary side to increase in current and overheat. Most other sizes seem to rectify harmlessly and can do that for many years, such as F40 size in NPF rapid start. In cases I've seen where a failed starter allows a lamp to rectify without blinking, the ballast doesn't seem to overheat either. I don't know about 240v choke ballasts though, such as in Europe.

A stuck starter will increase ballast current and heat no matter what and would depend on ballast quality and heat dissipation for how long it will last. Most cases would be bad, IMO.

Stuck starters are bad, but are an expected event in choke ballasts. Across the road from me is a fixture in a parkade that has been glowing at the ends for around 4 years now. Government building that has no preventative maintenance on the lighting, as only those lamps in the offices are changed on complaint ( might take a year or three to change still) but the entire garage area is lit by a few very sad very dim scattered survivors.