Q: Air Drop, LinkedIN, Vimeo - share extension missing

I have two Macs (Mid 2009 13-inch Macbook Pro & Mid 2011 21.5 iMac) and both systems are upgraded to El Captain.

The problem I'm having now with the Mid-2011 iMac is that the LinkedIN, Vimeo and AirDrop share extension is missing from the System Preferences. My MacBook Pro has everything intact after the upgrade. I'm struggling fin iguring out how to fix this or at least toggle them on permanently.

So far I've tried:

• Manually removed each accounts (LinkedIN & Vimeo) from the 'Internet Accounts' in the System Preferences - and then re-added each accounts back on
• Logged out of iCloud completely - then rebooted and logged back in
• Toggled Dashboard to 'As Space' (no changes) and as 'Overlay' (no change)
• Copied and pasted the widgets from /Macintosh HD/Library/Widgets to /user/ToddMorrison1/Library/Widgets
• Ran First Aid on the hard disk

I cannot figure out why AirDrop share extension is missing as well. As I mentioned earlier - my MacBook Pro has everything intact including the Air Drop share extension. I've no idea how to get Air Drop extension back on the list.

Another puzzling thing - I like accessing the calculator from the 'Today/Notification' side screen. After the update to El Captain, the calculator is missing from the side screen - I figured going to the Extension in the System Preferences and toggle it on from there, but alas the calculator is not on the list. Again, my Macbook Pro have this intact as well.

I've been searching around different forums and I'm not having any luck finding a guide how to add Calculator back onto the 'Today' extension list. Any idea how?

Any tips or links to some kind of guide will be very much appreciated.

Thanks in advance.