I recently fit some DMR pedals to a mates bike.

Today I noticed that the external shield (designed to create a seal between the Pedal Axle and main pedal body) has come loose.
There does not appear to be an obvious way to fix this – at first I assumed they were a press fitting but it would appear not.

Can anyone shed any light ?

Mine did the same. I just kept pushing them back on! Didn't seem to cause a problem.

yeha, mine have done that. I dont rate dmr pedals, I'll be buying new ones soon

Common problem. Not great pedals imo.

Congrats. You have just discovered that dmr stuff is mostly cheap guff.

yeh they all do that. And you'll notice that there's only one bearing cartridge in each pedal when you come to replace them.

If they are V12's just make sure you strip and fill with grease once they start to turn not-so-fluid – 10 min job.