I have a Duet and although I haven't owned it a long time I have just recently service the BB's. The spindle is a press fit in the bearings. There is a spacer inside but there are no 'stops' on the axle or any other feature that would lock the spindle in a given position, only the slight interference fit between the spindle and the bearing.
You can see from the picture the whole unit is held in by the snap rings. Yes he would need to remove the snap rings and press out the unit. I believe the once tight fit between the spindle and bearings has been compromised. I am the original owner of my 1990 Bongo and in addition to the snap rings there is what looks like epoxy. The OPs spindle used to have a press fit. A new BB set is needed. As I stated before I have used a jewelers or small screwdriver and removed the outer bearing seals several times in 30 years and worked fresh grease into them and replaced the seals. I bent my front spindle once. I had a Phil wood cartridge bearing set that had the same axle length at the time. I took it and the eccentric to a friends business and with his permission used his arbor press to take apart the Phil Wood unit. A then used the arbor press on the eccentric and removed the bent spindle and its bearings. The Phil Wood parts were compatible to the eccentric. the Phil Wood spec bearings had the same OD as the ones that had been pressed into the eccentric. I had taken a measurement of how far the left side of the spindle sat out from the bearing and was able to match it up. I did leave some info from Tandems East so the OP might get info or purchase parts.