The fix was simply to change the tension on the springs. There's
2 ways to do it.

You can do it normally by moving the spring to the next tension spot. Or you can insert a spacer, this makes the spring longer, and less tight. The spacker is made from something you make by
hand. If you're not handy then you have a problem.

without too much explaining. It's possible it would not shut because
there's too much tension on the spring. so loosening the spring means the door shuts easier thus completing its journey. you must
, however, cause the spring to be less springy , longer, both or somehow do this.

You can test the hypothethsis. Just ask someone to put a bit of
pressure on the door while it's closing , or opening.. which evern
is the problem mode. If it works ok then the spring is too tight.

Temperature can change the characteristics of the spring.

But oddly we have had the problem during periods whenthe temps
did not change much and not had the problem when the tmeps
changed a lot. so it's no fun diganosiging it.

Someone here can probably suggest a way to make the spring
looser or tighter as reqruired using a screw and washer or
maybe a piece of wood shim.

That solves part of the problem. I'm done for now. and will maybe check back to follow up a bit.

Andre