To remove moisture accumulated between the rubber and the window recess, there are drainage holes in the corners of the window recess. Be aware that when you close these holes or fill them with putty, the moisture collected cannot move in one direction and will therefore affect the recess of the window. Covered drainage holes are the most common reason for window recess rot and you can see it mainly in corners where moisture slips in.
When mounting the rubber, never use grease. First, it affects the rubber, which puts the drying process in the highest speed, and second, you use it to close the drainage hole. Use only glycerin, a product that does not affect the rubber and is thin enough to flow through the drainage holes.
To repair damage to the window rebate, there are several repair parts that replace only the rebate, or in some assemblies even a part below it. With all sets, you can only repair the bottom and sometimes part of the sides, if even the top is damaged, you will have to make a repair part yourself.
Useful information from Paruzzi magazine and from our YouTube channel :
Look for more technical articles on the page Paruzzi Magazine