Hi, thanks for al the replys.
i ended up fixing it, not without pain and extensive trial tests. I am electronic EE and play well with soldering iron.
Brass (or copper) tanks apparently cracked at various places, and a lot of tubes where seperated, since they are 2 pieces.
I straightened all the fins one by one with tiny long nose pliers.
I also added a external transparent tube so i can see the real level in it thru the front grill
I will show pictures soon as i have to get it out again because the water pump leaks...ARGH !!!!
can the water pump be rebuilded at all ??
thanks !!