E9 2.5V clear cylindrical incandescent bulbs

These bulbs are bought from a hardware store in 2006 which is still here today, but I am unsure whether the store is still selling them.
The rating of these bulbs are 2.5V 300mA, featuring a pointed tip. I bought 6 and found one of them was actually 1.5 volts rating (not shown in this video). The 1.5V bulb seems to have bad contact between its wires and the base, it will not lit without pressing the bulb tip.
One of the tested bulb seems to have problems, it flickers even the power supply is stable, while the others do not.

[@emiryedek2821]

ı have tiny lamps too !