I was going to try changing out the tube, but I'm having a devil of a time with the case screws. I can only get a couple of them to unscrew out from the case. The others are unscrewing at various angles or stopping halfway out. Very stubborn. I'm starting to strip some of the screws despite being very gentle and using different sized phillps. Admittedly I'm not too mechanically inclined I admit, but am I nuts - any suggestions?