Hello,
 
I am about to change the light seals on my Praktica MTL 3 since there is some kind of light leakage.  
I found only a strip of the old seal on the side of the hinge. There was no seal on the latch end and in the top and bottom slots of t

Every Praktica I've seen has string type seals in the top and bottom slots (but nothing at the latch). Are you sure they are not there? The hinge seal is the most likely to be the cause of the problem. I used 1.5 mm foam here, but 1 mm might do it.

I agree with Steve, my Praktica MTL 3 has string type seals top and bottom - nothing at the latch - and a fabric/velvet type seal at the hinge, this I need to replace with foam as it is falling apart. A nice solid, well made camera should last forev

Thanks for your answers,
 
I had a look again to the top and bottom slots and there were some kind of strings. It looked a bit like a twisted thread and I didn't count it as a light seal.  
I already changed the hinge seal with foam since I had