Hi. On virtually all Zeiss Jena binoculars, including your Dekarems, the oculars lift off after you have removed the central locking disk, which lies beneath the IPD plate. The locking disc on all models up to about 1985 is silver in colour and has two holes in it for a pin spanner/wrench. But look carefully and you will see a 1mm grub screw which has to come out before the disk will turn. You will need a 1mm slothead screwdriver to remove it. If it won't come out or you chew the head off, just drill it out with a 1mm or 1.5mm drill. Then unscrew the circular plate, using either a pin wrench or, if you don't have one, circlip pliers, which will usually be OK. With the disk off, the oculars simply lift of the shaft (but they may be a bit stiff so take it easy.) Also make sure that you don't lose the thin blue steel washers also on the shaft between each arm - they help maintain the tension on the arms and keep everything straight. Then clean the oculars, making sure you wipe off all the heavy grease around the lenses or it may smear onto them. Then re-assemble. Line up the tiny 1mm hole with its corresponding hole if you can. Or do like they did in the factory and just get the disk suitably tight and drill a fresh hole for the 1mm grub screw. Or if all else fails, use a little threadlock on the disk thread. Hope that is OK for you.
Regards,
Clive
