Flash player will not install

Mac OS 10.9.5

Safari 9,1,3

Existing Flash player 21.00.242

No Virus software running or installed.

Cannot get Flash player to install. Gets to about 70% and fails.

Then get directed to Adobe's "having a problem.... do this"

Nonproblem-solving page. Been there so many times I've

almost memorized it.

Tried Adobe's recommended procedures but no dice.

Been having this problem for a long time.

I could get it to install once a few months ago. Don't know

why it did. Surprised the heck out of me.

Any useful suggestions greatly appreciated.