Be sure to leave enough extra length to get the pipe cutter behind the ferrule, and then some. Probably the best way to go. One alternative is if you can find the plastic cover plates (chrome look) with the split in them. Most big box stores don't carry them, but some hardware stores do. (They look and work great and are not to be confused with the split metal ones that look too raw and industrial.) That way you could remove the valve, leave the nut on there, and install the plastic split cover plate (w/ chrome look) afterward.

My husband installed them and I assume he got them squarely on the pipe. It looks like if they weren't seated properly, they would have leaked immediately, not months down the road. We purchased these valves from Lowe's. We didn't buy the cheapest they sold because we wanted something that would last. You're right that it is difficult to see where the leak is. I stared at the drip for awhile and it *seemed* to be coming from the area you tighten to the copper pipe. It's definitely not leaking around the outflow connection.

I had a similar situation about a year ago, but I don't know much about plumbing, so I called a plumber. It seemed to me that this is the best option, but I was wrong. The plumber demanded a very large sum for his services, which was a great surprise to me. I didn't have the amount he wanted at the time and I refused his help. I decided that I'd rather save money and try to do it myself. Fortunately, there is a lot of useful information on the Internet that eventually helped me. I found all the necessary information about the valves at https://anixusa.com/gate-valve and it helped me find the right valve for my pipes. After a few hours, I managed to change it and everything was functioning quite well. From now on I fix my own plumbing at home

See video below. Neighbors tecumseh mower engine hit rock, bent blade and sheered flywheel key. Replaced key and blade. Engine starts, but will only run a few seconds. Trying to diagnose I am curious if it is normal that the exhaust valve slightly opens at the beginning of the compression stroke. i attached a video of what I am seeing. Thank you for assisting Mark