Iris diaphragm and front element of Artar 12 in. lens

[elio_napolitano]

Hi; I would like to fix the iris diaphragm of an Apochromatic Red Dot Artar 12 in. f:9 (#831381) lens, which is out of register, but I do not even know how to remove the front element, which appers to be a single piece with the barrel. I could only remove the outer diaphragm ring. The lens is of the type made of aluminum and is coated.
Thanks in advance for your help. Elio.

[elio_napolitano]

Hi; Problem solved. I finally managed to remove the front element after keeping the lens in the freezer for a while and using a rubber band for gripping.
Fixing the iris is quite obvious after the front element has been removed; I will be happy to give more detail for those who are interested. Elio.