Following a DAW external hard-drive change (details below) the MIDI functionality of my long-serving, trusted RME Multiface II seems to have been lost. The Multiface is central to a DAW that I rely on for a major part of my work. I'd be grateful for any help towards putting things right.

My DAW set up:
I-Mac 27-inch, MacOS 10.11.6 "El Capitan", additional monitor via USB 3.0/DisplayLink.
Thunderbolt to Sonnet 'Echo ExpressCard/34TB' bearing RME HDSP Cardbus, linked via Firewire cable to Multiface II.

Audio input: RME Octamic via optical cable to Multiface.

MIDI input control: Yamaha XP60 synth/keyboard with MIDI IN and OUT connected to appropriate OUT and IN on the Multiface front panel.

Monitoring: via TotalMix to Multiface II hardware outputs.

Logic 10.3.1.
Projects combine audio with software instruments, mainly EXS24 and Kontakt.

Recent changes:
All audio content for Logic, and many user-modifiable elements such as software instruments, sample libraries, patches and settings are on an external drive. I recently replaced this drive, requiring me to re-make many symlinks to get the DAW back to functionality.

I have not knowingly moved any explicitly MIDI-oriented DAW software components, but I have symlinked so many parts now that I may have missed something, OR I may have symlinked something that will not work via a symlink (i.e. that has to be on the computer hosting the DAW).

I have installed RME PCIe driver for Mac OS X Intel 10.9 and up version 4.13.
(For info: the version 4.21 download from the RME website is 'corrupted' according to my Mac, which will not unpack it).

I have run RME Flash Update Tool 2.9 for Mac OS X Intel 10.7 and up. Flash Update panel now shows: 'PCIe revision 20. Programming Status: Up-to-date.'

I have not changed or updated the MacOS in any way, nor any linked hardware, cabling, etc., apart from the external HD. The new HD is of exactly the same model and capacity as the one I've replaced (LaCie d2 2TB).

State of the DAW now:

Everything works except the functions that rely on MIDI via the Multiface II.

System Preferences > Sound: 'Hammerfall DSP Multiface (serial#)' is available for audio input and output.

Multiface indicator LEDS:
Green ADAT LED is illuminated when RME Octamic is connected and switched on.
Orange LED flashes in time with the clock output from the XP60 synth; it also illuminates when notes are pressed on the XP60. This behaviour is present and consistent as soon as the workstation is powered up, whether or not any applications have been launched. (MIDI events seem to be reaching the Multiface from the XP60, at least).

Apple Audio MIDI Setup > MIDI Studio panel: Multiface icon is greyed-out, although the correct serial# is shown for the device. 'Rescan MIDI' has no effect. In the device info panel (for the greyed-out Multiface) the 'Device is Online' checkbox is unchecked and also greyed-out.

Logic launch is interrupted by a pop-up panel with the following text:

"Instrument “XP60_” sends to a MIDI port named “Port 1” of MIDI interface “HDSP Multiface” which no longer exists. Please check if all MIDI interfaces are connected and switched on; otherwise adjust the instrument’s MIDI out port setting." (This is familiar, and usually addressed via 'Rescan MIDI' in Apple Audio MIDI Setup > MIDI Studio.)

Logic completes launch. Projects can be put into 'Play' mode and audio output reaches Total Mix as expected and can be routed to hardware outputs as normal.

There is no MIDI input to Logic via the XP60/Multiface.