filament errors, charger errors

I have a 9900 Elite that seems to work for 6-8 weeks after I fix it, then repeats the same exact errors. It shows charger failure several times then filament error. Ive changed the filament board, charger board, and HVRS board. Ive 100pc recalibrated the generator smack dab on the money. Works for maybe 5,6,7,even 8 weeks then repeats itself. GE told me that this can sometimes happen on obese patients. It maxes out 120KV and 8.3ma is where its maxed. Not sure what else to look at unless its a flaky tube. That I havent changed yet. It also has a brand new HV cable.