Today, at mid-night, the right of the three Gaash Hila lantern, that have a broken MV lamp, came back to life, and the lamp lit after a week or so that it wasn't operated.
One thing that I noted, is that the broken MV lamp in the lantern, varies in brightness , which its brightness and light intensity rises and falls randomally.
Sometimes the lamp is so dim that it is almost don't light the area, and sometimes it lights very strongly like an intact yttrium vanadate coated 125W MV lamp (But with a greenish white color).
What can cause this?

It could be that the temperature of the arc tube keeps changing so the light is varied.  It could also be that maybe it is just old and has a lot of hours on it so it has trouble keeping a stable arc.  It could also be a combination of both.  Hope this helps.

If this is erlated to atmospheric teperature (rain --> dim) then it may be arc tube temperature

Anoher option is bad connection, esp if corrosion is present. Since there are no moving parts, the connection may actually be quite stable, just with varying resistance (hot spot --> corrosion --> bad contac --> arcing --> welding itself a bit better --> heating less but new metal exposed and at high temp --> and so on)