Upon using the sillcock the first time in the spring water flowed out of the weep hole. Manufacturer said this would stop the leaking. It did. Removal of the old assembly required a pair of pliers to pull it free and a hammer (gently) to seat the new one. All in all a quick fix. What was not quick was the shipping an handling by the seller. Delivery took over two weeks. If you need it in a hurry order elsewhere.

When I turned our frost-free faucet on, it leaked out of a small hole in the stem right behind the faucet handle. I discovered on-line that this hole is referred to as a "weep hole" and acts as a drain to drain water out of the stem. The Web helped me identify the faucet's brand. I Emailed a picture to Arrowhead Brass support, and based on the picture and the color of the air vent cap (green) they identified the faucet as their 420 series and they Emailed me a 2-page repair guide. Plumbing is not my thing, so I watched a few how-to YouTube videos before starting, and I did the repair on a regular work-day just in case I would need the help of a plumber. Removing the Stem Assembly then the old Check Assembly PK2016 part from the end of the stem was fairly easy. However, re-inserting (snapping in) the new part into the stem simply by pushing it in by hand was impossible; it's too tight of a fit. I held the stem vertically with the valve end down on a padded surface and used a rubber mallet to tap and snap the new Check Assembly into the tubular stem. I also replaced the vacuum breaker air vent. The faucet now works like new. I understand from the literature that I read that frost-free faucets in general, require this occasional type of maintenance if the faucet is to last a long time.

The one being replaced can not be removed from the stem.

Right part that did the job. Found the right part using this guide: arrowheadbrass.com/op_champarrow/files/Frost-Free_Hydrant_Guide.pdf

easy to replace and stops leak-by.