Genalex Gold Lion KT-77 Compatibility Question

I love the sound of the Genalex KT-77's in my push-pull EL34 amp but I have now twice had the right channel tubes die on me within a 4-6 month period. After installing another quad in my amp I noticed, for the first time though it's certainly possible I missed it with past tube sets, that the two right hand tubes were glowing noticeably brighter than the two right hand tubes. So obviously, I think, the right channel is running hotter. I have not had this issue with any other tubes I have used and the amp recently had some minor service and is in perfect working order. So are these tubes simply not ideal for my amp? And generally speaking though they are supposed to be a drop in replacement for EL34 tubes are there differences in electrical or performance parameter between a typical EL34 or 6ca7 tube? I love the sound of these tubes in my amp but it's frustrating and annoyingly expensive to replace half a quad every 4-6 months or so, any thoughts from any of our more tech minded posters?