Thanks Peter but no, the BM1900 is very different in this aspect, having a damped closing of
the lid based on gravity rather than a damped opening based on a spring.
The arm, I need, is found only in Beomaster 2000 & 3000 of the 1980's and I believe also in Beomaster 3300.
I would consider a complete lid or even a whole Beomaster.
Martin