It may be worth doing a ramp test to check the focus point is right. Check all the optics are clean and are not discoloured. It may also be the the tube is on it's way out.
Using two LS3060's and an ex 3020 user
Please note I am not employed by HPC, any advice or recomendations I give are based on my own experience and are not necessarily the same as HPC's. First point of contact on any hardware issues should be with HPC