maybe your random way is allright, cannot say anything before seeing one working on screen..
it feels allright anyway.
But could it be better looking idea, if you move those 1-2 sprites from the arm towards the hook! As apart from punching enemies horizontally, telescope is used to climb UPwards or swing yourself sideways, and when you climb upwards, telescope arm of course winds itself up while you are rising, so that´s why i thought about if it would be nicer if sprites are moving from arm to hook. But again, cannot say how it will look like before seeing machine code version.
Anyway, I feel like 1-2 fast moving, random or not, sprites surely will give good illusion of metallic moving telescope arm!