The footbed inserts on Flex-on stirrups (similarly to the decorative inserts on the frame), can be easily changed by the customer if it has become worn or damaged (note this does not apply to the Endurance model). We stock replacement inserts which fit inclined or flat footbeds (regrettably, the mixed type are no longer available from Flex-on).
Fitting instructions: Under the footbed find the two small phillips-head screws that hold the footbed insert in place. Carefully remove the screws, then push through the holes with a suitable thin object (eg bradawl or paper clip) to lift the insert off its surround. Pull the insert backward (ie toward where your ankle would be) to free the insert from the locating slots in the front of surround.
To insert the replacement insert reverse the above steps.