Part of the problem, is that LGB changed the plastic it used several years ago, so iy depends a little on the age of the model..
Technicoll 8008 - I got mine from Bertram Hayn (sp?)
This is very-like a conventional polystyrene cement, in texture, and the way it behaves. - Has a life of it's own as it comes out the tube, strings a little, quite smelly in use.. But I have had some success with it.
The problem is many parts deform as they break, so you do not get a 'tight' join, so super-glues / Powerbond, and the like do not work well. That, and the 'greasy' nature of the plastic, make for poor adhesion.
Many breaks, are parts which are stressed in some way, hence an ordinary glued-joint does not hold.
Others have reported success with 'real' Methyl-Ethyl-Ketone (MEK). - Not the concoctions sold for modellers, the real-stuff. - Smelly, and needs treating with care!
PhilP.