Hello Drix,
I have the same machine, though it is still is not functional. The main problem as you are finding out is sourcing parts.
On my machine the thermostat is shot and I will eventually replace it with a pressurestat. Another difficulty is that it has no water level gauge, though this can be worked around by filling every use.
The piston head on my unit was also corroded and pitted and I will have a new one machined one day.
This was the condition
And now the soft parts, the piston gaskets are hard to source but I have bought a double flanged one (they did not have the single flanged) made for the baby Riviera, I got it from a shop in Montreal named
http://www.espresso-mali.com/.
I think the machine may work with three double flanged gaskets but still would prefer to rework the piston head before buying gaskets. It has been a long and slow moving project. But the machine is a beauty and one day it will be working again.