The Mod 50, covering the 3 ball trigger is covered in the Idiots Guide sticky in Collectibles, 61, 62 and 92.
The 35 is a bit simpler to strip down but has the same trigger.
I have instructions for the 35 and if your profile has an e mail I will send them to yoy ... but there is nothing really tricky about it.
Cheers, Phil
Just looked. No e mail. If you send it to me by PM I will send 35 details.