Agree with @mck414 - dig out around the head (to keep dirt out of the pipes), unscrew it, take it to an irrigation supply place and get something that looks just like what’s in your hand. And maybe throw a couple wraps of teflon tape on the threads when you replace it.
Yep. Just a couple laps around - it’ll ensure a good seal and keep the threads from seizing.
I had a summer job in HS installing an irrigation system on a golf course and we taped all threaded joints.
I would dig them up to keep dirt from getting inside. Then, put a drink bottle or something over the pipe while you’re working around it. You want to check to see what diameter fitting the sprinkler heads need because some are 1/2 inch and some are 3/4.
Just a tip. When you dig up the grass and dirt, put it in a bucket or small tarp. If you put it on the grass nearby, a fair amount will fall into the grass meaning that you don’t have enough to fill the hole. And trust me, you never want to have a problem with not properly filling the hole.
For mine, I didn’t need to dig them up nor did I put on teflon tape. My heads were shaped such that the pipe they screw into fit up inside the head. When you unscrewed the head the pip you exposed was clear of the surrounding dirt. No teflon because a few drips in the dirt wouldn’t be a big issue like a leaky faucet would be. Ours look like this:
I guess whether you need to dig it out depends on your soil. In Florida, we don’t have soil - we have sand. It doesn’t compact and the sides constantly fall in when you’re digging a hole. In Chicago he probably has equal parts mafia bodies and poo from Wisconsin.
I replaced all of mine and the timer last year. The nice feature of the sprinkler heads I used was that the spray pattern was adjustable. Used to be you bought ones that were full circle, or 3/4, 1/2 etc. Much easier to just buy them all and not have to keep a list of how many for each spray pattern