copy left to missing right channel [SOLVED]

New user here, elementary stage at the moment.
I am converting an old cassette to CD-R which has about 20 seconds where only the right channel drops out in the middle of a piece in the original media.
I’d like to copy the left channel onto the right for that same section of time using Audacity, just to fill-out the missing music on the right channel.
It’s amateur organ music with not a great deal of L-R difference, so not looking for audio perfection, just an ok fix.
Is there a simple idiot guide to do this? so far I have not found the answer in the on-line help but would be glad of advice.
OOPS sorry, meant to say Win 7, latest version 2.1.1, and exe

Select the track where the missing bit is and a bit either side.

Click the Zoom to Selection

Select again but only where the gap is

Apply a mono effect set too low to make a difference

That should do it

Re: copy left to missing right channel.

There is a Audacity plugin called “Channel Mixer” which does that …

Channel Mixer …
A multi-purpose tool that can perform almost any type of channel mixing task on an unsplit stereo track.
Typical uses include:
Copying one channel of a stereo track to the other channel >[b]Channel_Mixer[/b]

You may have to use Audacity’s repair to hide the joins.

To disguise the fact the track has gone mono during the 20-second repair, you could apply pseudo-stereo to the whole track.

Many thanks for the advice.
I did get it fixed in the end, even if it did sound a bit odd.
The stumbling block before doing a cut and paste was figuring out how to separate the two L&R channels.
After that it was fairly plain sailing.
Thanks again.