There are two blade aerials underneath the aeroplane, one for the transponder and one for the DME. I'm not sure which is which. One of them is a fairly new CI-105 and the other an older CI-105-6 (shown above). Needless to say the CL-105-6 is the more expensive to replace, and is the one that is now in two pieces.
Of late the DME has been playing up. It managed to pick up a signal at Goodwood recently, but only when I was on the ground and 0.1nm away from the transmitter. That suggests some kind of aerial or connection fault (the DME itself works fine with test equipment) so it could be that when the shiny, new, expensive aerial is fitted that all will be well, or it could be that the fragile worn and now broken aerial was actually the transponder aerial, and that the DME remains broken (it is a Narco, so that wouldn't come as any great surprise).