You may notice that the icon of your phone has changed to the Nokia 3650 (which 5.06 as a default) and this makes all of the difference. Because iSync thinks that you have a 3650, it tries to connect with it differently.
To fix this, you need to navigate to (and open) the SupportedDevicesInfo file (I wound up using sudo and pico to edit the file:
% sudo open -e /System/Library/SyncServices/SymbianConduit.bundle/\
Contents/Resources/SupportedDevicesInfo
In this file, you will need to replace the 7650 ClassId with the 3650 one and erase the 3650 section. Here's my new file (I've also taken out the 3600) -
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN"
"http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>N-Gage</key>
<dict>
<key>ATI3Response</key>
<string>Nokia N-Gage</string>
<key>AgendaDatabasePath</key>
<string>c:\system\data\calendar</string>
<key>AgendaMappingsPath</key>
<string>3650AgendaMappings</string>
<key>ClassId</key>
<string>5243396</string>
<key>MappingsPath</key>
<string>3650mappings</string>
<key>iSyncIniPath</key>
<string>c:\system\iSync.ini</string>
</dict>
<key>7650</key>
<dict>
<key>ATI3Response</key>
<string>Nokia 7650</string>
<key>AgendaDatabasePath</key>
<string>c:\system\data\calendar</string>
<key>AgendaMappingsPath</key>
<string>7650AgendaMappings</string>
<key>ClassId</key>
<string>5243396</string>
<key>MappingsPath</key>
<string>7650mappings</string>
<key>iSyncIniPath</key>
<string>c:\system\iSync.ini</string>
</dict>
<key>P800</key>
<dict>
<key>ATI3Response</key>
<string>P800 Bluetooth (TM) Modem</string>
<key>AgendaDatabasePath</key>
<string>c:\documents\agenda\agenda</string>
<key>AgendaMappingsPath</key>
<string>P800AgendaMappings</string>
<key>ClassId</key>
<string>1057292</string>
<key>MappingsPath</key>
<string>P800mappings</string>
<key>iSyncIniPath</key>
<string>c:\documents\iSync.ini</string>
</dict>
<key>P900</key>
<dict>
<key>ATI3Response</key>
<string>P900 Bluetooth (TM) Modem</string>
<key>AgendaDatabasePath</key>
<string>c:\documents\agenda\agenda</string>
<key>AgendaMappingsPath</key>
<string>P800AgendaMappings</string>
<key>ClassId</key>
<string>5251596</string>
<key>MappingsPath</key>
<string>P900mappings</string>
<key>iSyncIniPath</key>
<string>c:\documents\iSync.ini</string>
</dict>
</dict>
</plist>
Save the file, remove the device from iSync and set them up again. Worked great for me.

