Problem with flash plugin

[silverback]

My Firefox (version 39) currently has Shockwave Flash 17.0.0.190. Firefox has disabled this because "it is known to be vulnerable and should be updated". I follow the 'update now' link and arrive at an addons page which says that "Flash Player Plugin 16.0.0.305 to 18.0.0.193 (click-to-play) has been blocked for your protection."
I am urged to go to the Plugin check page where it says to click the Update button - but there isn't one. I just get the rotating symbol meaning the page is loading. I left it for an hour but it was still doing this when I came back.
I can't see how to delete the Shockwave plugin so I'm baffled as to how I can update to a newer, safer version.
Any hints, please?

Thanks
Silverback

PS : This problem means the Eileen's Lounge Clock on the Portal page just displays a message saying "This plugin is vulnerable and should be updated." Clicking on the update link takes me to the page mentioned above.

[stuck]

Get Flash from here:
https://get.adobe.com/flashplayer/

NB, unless you want the 'optional offer' make sure you untick that box.

Ken

[HansV]

Alternatively, see the links in Update: Flash Player 18 released for the stand-alone installer (no fly-by software offers).

[silverback]

Thanks, Ken and Hans
Took Ken's advice and it failed so I switched off Avast shields (nervous!) and it installed OK. Lounge clock back and working.

Thanks both
Silverback