pitless adapter question

Hello, I am in the process of connecting the pitless adapter in my well but am having some problems. My well is 680 ft deep, so this has been a difficult process. There is a PLASTIC check valve in my Jacuzzi 2HP pump that went bad. I've replaced it with a brass check valve which seems to be holding the water in the line. I was also having a 2nd problem at the pitless adapter which was allowing air to seep into the well line and into the house. I saw a lot of corrosion and took the o ring out and cleaned it, gooped it with vaseline and put it into place again. Pushing the o ring back in was a little difficult because it would not seat properly. If you push it in place at the top it would come out a little elsewhere. While the tractor was lowering it and the pitless was being lined up it sliced the o ring and would not seat properly without slicing it. Assuming this was human error, we redid the process and have lost a 2nd o ring the same way. What am I doing wrong? Should I have put the lubricant in before placing the o ring in the groove the way I did, or is this why it is wanting to pop out. Should I put the o ring in without lubricant and then lubricate just around the outer face of the o ring? It is the correct o ring for the pitless adapter, any ideas? Thanks in advance!!
Heather

In all my years of pump/well service I never had to replace an O ring in a pitless. I would clean our the O ring grove the best I could, dry it and install the O ring dry into the groove. Then lubricate the face of the O ring and reinstall the slide in portion of the pitless and his should do it.

Always keep in mind everyone is an expert at a distance. . . you are there and only you really know what's happening. A friend of mine says that a "Consultant" is a mechanic from out of town and he's pretty much right!

I have had several pitless units where the o-ring gets sliced everytime I set it down. I use the next size smaller o-ring. I have to stretch it over the fitting a little, which makes the o-ring smaller in diameter. This has worked me me several times.

Found out that the problem was the t-bar that we used to lower the part to connect to the other half of the pitless adapter was bent. Straighted out the bar and it slid in, no problems. Thanks for the advice.

Heather