I just found out the cause of the problem and fixed that, it wasn't the sticky foam but a mechanical fault, since I'm not a mechanic I try to use layman terms to explain the process.
Remove the bottom plate you will see as shown on the photos, there is a tiny piece of 'spring catch' thing gone out of position to prevent the mirror to release, simply bend it slightly to the right to clear it's way.
1. Standby position shutter and mirror released.
2. Winded up ready to shoot.
3. Spring Catch does not return after release.
4. Bend the spring catch slightly to the right to fix that.
I don't know exactly what caused that, but the shutter worked normally after the 'fix' so I will leave it that way, I can't expect this 'ancient' camera works like new anyway !