I was watching television the other day when the picture began to get jagged. It does that sometimes — clearly a problem with the cable signal.

Forty years ago, in the days when there were just three or four channels, I could have fixed this kind of thing myself.

I’d have grabbed the upside-down coat hanger stuck in the broken antenna shaft and twisted it just so. Problem solved.

I was a master at fine-tuning TVs by coat-hanger. It’s now a lost art. I suppose it’s for the best, but I spent a lot of hours working on my hanger-expertise — all for naught.

It got me thinking about other skills I once had but no longer need.

For example — popcorn. If the microwave broke, I’ll bet most people under 30 would be lost. I wouldn’t. I still know how to take out a pan, pour in so much oil, sprinkle in just enough kernels, and cook it over a burner until the top begins to bulge. The trick is knowing you have to keep shaking the pot almost violently. But it’s now an unneeded skill.

Once, I was going to be a photographer when I grew up. I got pretty good at threading film perfectly into cameras. Overdoing it would waste film, and underdoing it would be a catastrophe: You could shoot 36 pictures and find the film never advanced. I knew how to thread it right, every time. A lot of good that does me now.

It was my job to help take out the garbage. The cans were all made of metal. They were always heavy, and none had wheels. Dragging a full one flat was arduous. But tilting it at a perfect angle — not too much or it would spill — made it pretty easy. I still know how to do that.

Just as I know how to turn on high-beams by stepping on the floor button. Especially with a standard-shift car, you had to know the spot by instinct in case you had to dim and clutch almost at once. I could do that. But I haven’t come across a floor-button for brights in years.

Anyone who had a turntable knows the challenge of setting the needle on a record’s rim. If you drop it from too high, you damage the needle, and if you’re off by a millimeter, you miss the song’s start. I got so good at it I could drop the needle at cuts between songs in the middle of the record. But I don’t think there’s a need to do that with my iPod.

I also have no more need to sandwich a carbon sheet perfectly between two pieces of paper — then rolling them into a typewriter to make copies. If you were sloppy, the sheet smudged. Not with me — I had carbon-paper skills. I was also adept at threading white-out into the typewriter hammer slot. Today, I take care of those functions with the copy or delete buttons. It’s easier, of course. But man, I was good at carbon and white-out.

Amazon is easier, too. But if the Internet died, I’d still be able to look up books in those little library drawers filled with cards arranged by the Dewey Decimal System. Do they even have those drawers anymore?

I used to get impatient dialing a rotary phone, especially if there were a lot of 0’s in the number. But I got good at forcing back the dial counter-clockwise to speed that up. I don’t get to do that with my cell.

Just as I no longer can use my ability to fill Green Stamp books to get free stuff, or pour out a new box of cereal into a bowl to get the prize at the bottom, then pour it back into the box without my mother knowing it. Why doesn’t cereal come with toys anymore?

I know how to play tennis with a wooden racket, and I’ll bet my kids would have no idea what a “racket press” is. I do. If I still had my Poncho Gonzales racket, I’d ratchet down the press, and it wouldn’t warp, I’ll tell you that.

I love step-in ski bindings, but if need be, I could secure my boot with a cable going around the heel and a front lever locking it. And once on the slopes, I’d be able to grab a tow-rope — without lurching forward or ripping my gloves — to go uphill.

No one seems to dress for an airplane flight anymore — security makes you undress instead — but I knew and still know how to put on a tie “just” for travel if I had to, which I don’t. And thank goodness there’s no smoking on flights now, but if there was, I’d know how to avoid the seat row just in front of the smoking section since you used to get nailed there.

Finally, I know how to wait for four days for a mailed letter to arrive. I don’t think my kids have that skill. If they don’t get a text back in 30 seconds, they get antsy.

I was talking about this with a friend and he told me something that makes a fitting postscript.

He said he recently got a handwritten thank-you note.

“I was impressed,” he said. “I thought handwriting letters were a dead art.”

He decided to tell the sender how impressed he was.

My friend composed such a note.

And sent it by e-mail.

mpatinkin@projo.com