Need recommendation for replacement of Vintage Conrad-Johnson PV-11 preamp.

My vintage Conrad-Johnson preamp developed a problem wherein the right channel is louder than the left.  I changed all the tubes and the problem went away -- for two days.
Now it's back.  I'm wondering if it's worth fixing or whether I should get a new or used preamp.
i LOVE the sound of it when it's functioning properly.
If I can't get it fixed, can anyone recommend a preamp that might have the same qualities of a vintage Conrad-Johnson?