After a few days I managed to mount the new rudder. At first I had to remove the old rudder. Not too hard except that the mounting screws weren't too good. Then I needed to find some new mounting screws. After seeing the screws I decided to go for some stainless steel 3mm wood screws. That proved hard to find and obtain, so I ended up buying some 3mm X 18mm self tapping titanium screws. They will not rust. The new rudder only takes two mounting screws and at a different hole distance from the old rudder. This meant I needed to fill out 3 of the old screw holes. That was done with a medical needle and some epoxy so I could fill the screw holes from deep within. Then after letting the epoxy set for 2 days, the mount surface had to be flattened and painted. Needle files were used for flattening and Humbrol no. 191 was used for paint. After two layers of paint the rudder was ready to be mounted. That was actually quite easy. At first I made sure that the remaining screw hole was big enough for the new screw. That was done with a 2mm drill. Then I secured the mount bracket with one screw in that hole. With the first screw and the mount bracket in place, I drilled a hole for the second screw and secured that screw so the bracket was in place. Then it was just a matter of putting the rudder on the bracket.See the pictures below for illustration.