Hey Mark

just for the record the wood frame of the flap servo is not 90 degrees with the flap hinge and that can cause binding in some positions...
but its an easy fix with an extra spacer of wood on one servo side to bring it closer to 90degrees with the hinge line...

5645 is strong and will handle your flaps!If i recall corect there should come with there clasic blue aluminium arm ?!

If yes use it! ...it takes a long link but works...here is my set up on the L39 with hs7955tg and use a triple switch with delay.......any videos of your L39 fly??

cheers
George