MacBook Pro Mid 2012 Display rarely comes up after sleep or restart

A couple of months ago I started to have trouble getting the display on my MBP to wake up after sleep. Only way was to force shutdown and restart. Initially it would come back up after the first or second try. Now, I usually get the startup chime and Apple logo on screen for about 5 seconds before the screen once again goes dark. Sometimes, I get no logo at all. And rarely I get no startup chime.

Keyboard backlight works as well as light on caps lock--every time I boot.

I've tried the SMC and PRAM reset... no help.

I've looked through the forum here and one good tip that I've yet to try is shining a light through the lid to see if there are any onscreen graphics at all.

I was marginally OK with the idea of leaving the machine on my desktop powered up all the time... at least it worked. But now it's begun to fail during use. And sometimes requires 25 tries, (force shutdown and restart), to get the display to actually work. Which isn't much help. I've managed to get the SSD backed up via Carbon Copy Cloner. Hoping that there might be a fix for this that doesn't require replacing hardware.

Yes, I realize it's a 5 1/2 year old machine. But up until this problem appeared, it's been freakin' amazingly bulletproof. Oh, and never dropped, no spills, no abuse.

Any ideas?

Thanks!

Tom