It is surprising that the 'chip' template is different to the magnetic version. After all the tunnel is the same size. In the end our friend Ahmet resolved the problem by drilling a new set of holes; there were more than enough already but in the wrong place with regard to our double glazed panel. We capped the external screws with the old fittings. Internally they are waiting a coat of tippex. The door itself is sturdy enough and of the same quality as our previous one. 4 stars for all our trouble. Either a design flaw or a conspiracy with the glass manufacturers.