Annika,
I'm French, so ...
I own the Laborator 1000 (ancestor of the 1200) and the CLS450 head.
If you've questions, feel free to ask.
The head has 2 style of power spply : a plain transformer one and a stabilized version. This later one is full of 1970 electronics and would be a nightmare to repair if it goes south.
Both share a nice device to start the head fan after some time and to keep it running for some time after the exposure. It helps lenghten the lamp life...
Double and triple check the solders in the plugs. The wires carying the lamp current are soldered on many pins in the plugs in order not to fry the pins. If some joints are bad, expect very low lamp life or sparks into the connectors.
It could be wise to change the lamp socket if the pins seems to have suffered from heat. They can be found in a store selling general lighting parts. Buy premium quality. It pays.
Last but not least, the head fan runs at mains voltage. Keeps your hands of !
Hope this helps.