hi heli
i had a bulb shutter release just like the one you have.
it worked nice for a little while, and then it stopped
working. the "throw" stopped coming out and going in, as it
had done before, and on one of them, the black part
( the part you hold when you screw the release into your camera )
separated and fell apart.
unforunately i think these air-bulb releases are not made
as well as they could be made. i decided to get a degroff shutter release
- the rolls royce of shutter releases. it has a long hose and is beautifully made.
i got mine new for about 65$ USD, but you can find olde degroff pneumatic cylinders
(brass+engraved) on ebay,
and buy surgical hose and a blood pressure cuff bulf and
you will be good to go

...
good luck!
john