Root Getting Galaxy S to boot into CWM recovery

[Amphibian59]

Following my previous thread about problems with ICS, I have now flashed the phone back to GB 2.3.3. Everything is working fine, and the phone is still rooted. Now I want to install another custom ROM, and have copied it to the SD card, but the phone refuses to boot into CWM recovery which I know is on the phone because it was installed with CF Root. It always boots into stock recovery, so the ROM fails to install. I have seen that I can install the CWM app using ROM Manager, but is this safe? I suppose it should be as it's on Google Play, but I have seen reports of problems. Please advise.

Also which custom ROM is recommended if I want to upgrade to Jelly Bean? I am attracted by Avatar, but RemICS installation looks a bit more complex.

 

[Amphibian59]

OK, I got impatient and installed ROM Manager. But the phone still refuses to boot into anything other than the stock recovery. I have CWM and TWRP, and set ROM Manager for each of those in turn. When they didn't work I installed CWM again via ROM Manager. But because the phone booted into stock recovery it failed to install a new CWM. I really need to disable the stock recovery. How do I do that?