No problems with the tube vice as yet!. And the position of the rca feels great...it feels a bit like a neuma in the hand only a lot lighter...especially with a nylon grip...Ive only used them for 1 day but really enjoyed them....Got lots of experimenting to do with the colour give inserts but used yellow(the softest) for shading and tried green and red for lining...its early days but im liking them ...