Hi Linc,
Many thanks for all your help. I hope the following extract from my Console Log makes sense and identifies a solution:
[I have replaced my name with XXXXX]
19/05/2014 19:00:55.693 iTunes[4348]: Entered:_AMMuxedVersion2DeviceConnected, mux-device:2
19/05/2014 19:00:55.724 iTunes[4348]: tid:19433 - unable to query device capabilities
19/05/2014 19:00:57.427 com.apple.usbmuxd[25]: LOCKDOWN_V2_BONJOUR_SERVICE_NAME is _apple-mobdev2._tcp,8e6707f5
19/05/2014 19:00:57.952 SyncServer[4394]: [0x7fd4896066c0] |SQLite|Error| Detected out-of-space situation: 0 (Undefined error: 0). 485217927168 bytes free in XXXXX
19/05/2014 19:00:57.953 com.apple.launchd.peruser.501[173]: (com.apple.syncservices.SyncServer[4394]) Exited with code: 1
19/05/2014 19:00:59.033 iTunes[4348]: [0x600000874440] |Mingler|Error| failed to connect to the server: NSInvalidReceivePortException connection went invalid while waiting for a reply because a mach port died
19/05/2014 19:00:59.185 com.apple.launchd.peruser.501[173]: (com.apple.syncservices.SyncServer) Throttling respawn: Will start in 9 seconds
19/05/2014 19:01:08.202 SyncServer[4396]: [0x7fba9840bd30] |SQLite|Error| Detected out-of-space situation: 0 (Undefined error: 0). 485217923072 bytes free in XXXXX.
19/05/2014 19:01:08.203 com.apple.launchd.peruser.501[173]: (com.apple.syncservices.SyncServer[4396]) Exited with code: 1
19/05/2014 19:01:09.193 iTunes[4348]: [0x600000874440] |Mingler|Error| failed to connect to the server: NSInvalidReceivePortException connection went invalid while waiting for a reply because a mach port died
19/05/2014 19:01:09.345 com.apple.launchd.peruser.501[173]: (com.apple.syncservices.SyncServer) Throttling respawn: Will start in 9 seconds
19/05/2014 19:01:18.430 SyncServer[4397]: [0x7ff310c068a0] |SQLite|Error| Detected out-of-space situation: 0 (Undefined error: 0). 485217923072 bytes free in XXXXX.
19/05/2014 19:01:18.431 com.apple.launchd.peruser.501[173]: (com.apple.syncservices.SyncServer[4397]) Exited with code: 1
19/05/2014 19:01:19.351 iTunes[4348]: [0x600000874440] |Mingler|Error| failed to connect to the server: NSInvalidReceivePortException connection went invalid while waiting for a reply because a mach port died
19/05/2014 19:01:19.503 com.apple.launchd.peruser.501[173]: (com.apple.syncservices.SyncServer) Throttling respawn: Will start in 9 seconds
19/05/2014 19:01:28.590 SyncServer[4399]: [0x7ff5bae068e0] |SQLite|Error| Detected out-of-space situation: 0 (Undefined error: 0). 485217923072 bytes free in XXXXX.
19/05/2014 19:01:28.591 com.apple.launchd.peruser.501[173]: (com.apple.syncservices.SyncServer[4399]) Exited with code: 1
19/05/2014 19:01:29.511 iTunes[4348]: [0x600000874440] |Mingler|Error| failed to connect to the server: NSInvalidReceivePortException connection went invalid while waiting for a reply because a mach port died
19/05/2014 19:01:29.662 com.apple.launchd.peruser.501[173]: (com.apple.syncservices.SyncServer) Throttling respawn: Will start in 9 seconds
19/05/2014 19:01:38.739 SyncServer[4400]: [0x7fb0425066c0] |SQLite|Error| Detected out-of-space situation: 0 (Undefined error: 0). 485217914880 bytes free in XXXXX.
19/05/2014 19:01:38.740 com.apple.launchd.peruser.501[173]: (com.apple.syncservices.SyncServer[4400]) Exited with code: 1
19/05/2014 19:01:39.669 iTunes[4348]: [0x600000874440] |Mingler|Error| failed to connect to the server: NSInvalidReceivePortException connection went invalid while waiting for a reply because a mach port died
19/05/2014 19:01:39.820 com.apple.launchd.peruser.501[173]: (com.apple.syncservices.SyncServer) Throttling respawn: Will start in 9 seconds
19/05/2014 19:01:48.906 SyncServer[4401]: [0x7fdb33c0bc10] |SQLite|Error| Detected out-of-space situation: 0 (Undefined error: 0). 485217910784 bytes free in XXXXX.
19/05/2014 19:01:48.907 com.apple.launchd.peruser.501[173]: (com.apple.syncservices.SyncServer[4401]) Exited with code: 1
19/05/2014 19:01:49.828 iTunes[4348]: [0x600000874440] |Mingler|Error| failed to connect to the server: NSInvalidReceivePortException connection went invalid while waiting for a reply because a mach port died
19/05/2014 19:01:49.980 com.apple.launchd.peruser.501[173]: (com.apple.syncservices.SyncServer) Throttling respawn: Will start in 9 seconds
19/05/2014 19:01:59.068 SyncServer[4403]: [0x7f97f0e066a0] |SQLite|Error| Detected out-of-space situation: 0 (Undefined error: 0). 485217910784 bytes free in XXXXX.
19/05/2014 19:01:59.069 com.apple.launchd.peruser.501[173]: (com.apple.syncservices.SyncServer[4403]) Exited with code: 1
19/05/2014 19:01:59.987 iTunes[4348]: [0x600000874440] |Mingler|Error| failed to connect to the server: NSInvalidReceivePortException connection went invalid while waiting for a reply because a mach port died
19/05/2014 19:02:00.139 com.apple.launchd.peruser.501[173]: (com.apple.syncservices.SyncServer) Throttling respawn: Will start in 9 seconds
19/05/2014 19:02:09.156 SyncServer[4404]: [0x7f8c1040bc10] |SQLite|Error| Detected out-of-space situation: 0 (Undefined error: 0). 485217894400 bytes free in XXXXX.
19/05/2014 19:02:09.157 com.apple.launchd.peruser.501[173]: (com.apple.syncservices.SyncServer[4404]) Exited with code: 1
19/05/2014 19:02:10.145 iTunes[4348]: [0x600000874440] |Mingler|Error| failed to connect to the server: NSInvalidReceivePortException connection went invalid while waiting for a reply because a mach port died
19/05/2014 19:02:10.296 com.apple.launchd.peruser.501[173]: (com.apple.syncservices.SyncServer) Throttling respawn: Will start in 9 seconds
19/05/2014 19:02:11.126 spindump[4405]: iTunes [4348] didn't gather any samples due to audio running
19/05/2014 19:02:11.140 com.apple.launchd.peruser.501[173]: (com.apple.iTunes.35760[4348]) Exited: Terminated: 15
[I needed to apply a Force Quit to terminate iTunes]
The error message seems to be looping ....
Best wishes
Simon