8 x 40 Hunter macro( how to focus on infinity)?

[Lux1]

I brought an old pair of binoculars from a car boot sale for a couple of pounds, the centre cover over the bridge screw is missing, however I'm sure they are 8 x 40. They are vintage Japanese and quite bulky.

Anyway, the prisms and objectives were covered in dust and dirt, I carefully stripped everything down, removed and cleaned the prisms and reassembled. Collimation remained perfect. They are spotless and give a super sharp image.

However, as macro binoculars they are designed to focus on objects very close to the observer such as birds etc ( feathered type, naturally), - they will focus on the moon but the focus is right at the end of the adjustment, background stars could do with just a little more tighter focus, which I don't have.

Is there any adjustment or modification I can make to have them better suited for star gazing?