CAT SL-1 Reference repair

I recently bought a CAT SL-1 Reference preamp. The line stage is great. But the phono stage doesn't work properly. I crank up the max volume but it doesn't give reasonable listening level and it became too noisy. The sound is dry and week.  It doesn't balance well either.  I replace all the tubes in phono stage but without luck. Anybody has a schematic of this preamp? I didn't find anything on internet. Any suggestion is appreciated. Thank you.