I'll throw a few things out there. The DS needs to be threaded into the BB shell first until it butts up against the shell, then thread the NDS until it stops. If you already have done that find a thin blade of some sort and carefully pry off the bearing seal to check the condition of the bearing balls and if there is enough/any grease still there. If not, pack with grease and try it out. At 10k kilos it should be just breaking in at this point. Also the concentric (eccentric?) BB shell may be a little too wide as you said you replaced the original BB it may have a different width. Road is 68mm, mountain is 73mm wide and may have worked OK for some time but eventually became loose.