Vertical casement window 36 x 48 , crank arms guides. etc

I need to replace the sill crank arms and top guides and whatever is need to repair these windows, I think Viwinco is the make. They are 10 years old and a bad idea especially for a house 3 blocks from the Atlantic Ocean. I saw a parts fir the bottom but not the top. I would greatly appreciate any help and guidance, thank you in advance! Tom