Does anyone have any advice as to how to remove arms from Star Wars kubricks, particularly protocol droids? Please don't say get a Wookiee to do it

They are fictional characters and not very helpful in real world scenarios

I thought it would be easy to give it a bit of force (seriously these puns are not intended) but I don't want to destroy it and the shoulder cover gets in the way. Even playing around with the removable limbs shiny C-3PO which is supposed to come apart I had to remove the whole chest section and head.
Very minor the Force Awakens spoilers to follow.
I've wanted to make an episode 7 C-3PO for a little while now (since someone posted blurry pictures of some crappy merch with an image of C-3PO and R2 on it) but now after Comic Con I'm more comfortable mentioning it and wanted to try and put a R-3po arm on C-3po. I've even got a spare R-3po and half a dozen different C-3po's to do the job.