I may be the idiot here, but how can you punch in with Reaper? You don't want to punch in anything even if you do record, and since you haven't even recorded anything, what could you mean by punching in? Either I'm totally wrong, or you're not using the DAW as intended. I'm going to spell out what might be obvious to some people, but making any assumptions when people need help is just asking for more confusion.
So, maybe you are running a virtual routine to figure out how to "punch in" when you need to record, but even then, why punch in when the beauty of digital audio workstations is non-destructive edits?
If you're trying to build editing skills, what you should do IMO is take your resources (files and applications for creating files) and place representations of their files on to your virtual tracklist timeline. The software records your editing decisions by representing them visually. Every time you add a track, it creates a horizontal place for the recording to be represented, whether recording MIDI or audio wave files. The same space can be populated by dragging files to the same area of the timeline. I assume when you say punch in that you are dragging files to the track timeline.
For example, if you're using a technique with loops, you would place a wave / audio file representing a riff on to the track in the timeline that represents when the riff will play in your project. The drums will not be on the same track. You do them on their own track, and the timeline synchronizes their playback in your finished product.
When I envision the process I just described, I can't imagine what you'd be doing that sounds like this:
"I've started dropping into guitar tracks to re record guitar parts but when I've choosen the guitar track I want to keep out of the previous recording and the new take"
OK, dropping guitar tracks...I assume you mean the wave audio file representing a riff rather than an entire recorded performance? Or maybe you are using a long performance without looping?
By "take" you are saying you have various versions, or adjustments to try, then you play it as a "take." When I hear "take" I think of actual recordings, not editing decisions, but as long as we understand each other, we can solve the questions. Think of every change you make to the timeline as an editing decision. That is why you can save each version under a new project file name without growing massive new resources. You're simply recording editing decisions if you haven 't made any new recordings. Virtual recordings are just editing decisions. You don't destroy anything, nor do you create anything until you render output. Is that what you're doing? Is that what a take is, instead of listening to your editing decisions on the timeline, you're rendering output?
The next question is, since we should assume nothing, are you using a MIDI track in Reaper to record or place MIDI events for your drums, or are you rendering the output as audio and importing the drums as wave / audio files?
If you want to, we can figure out a way to look at your files and I can set them up in Reaper, which I also use. I'm on the current 4.something.
Take the project as you describe it, and list the files you use, including extensions and how long the file plays in your project. For example, guitar-track.wav or guitartrack.mp3 at 4.whatever seconds, and drumtrack.wav or drumtrack.mid or midi at 5.whatever minutes.
If you don't want to list the whole project that way, list at lease the elements you are asking about.
Your questions simply require too many assumptions, but it also seems like you assume there are not so many varied ways to use the software. Most requests for help rely on too many assumptions, and the errors are almost always within those assumptions.
Also, if I am totally wrong, it will still help to list your hardware and OS specs, RAM and CPU etc. If you have a relatively new DirectX video card, list that too, because they handle a lot of the audio processing if you use a directsound driver (for playback in this case, which is very likely the case since you have no audio recording-centric interface).
That is all I can think of for now. I some times don't get back here to look up threads I'm following, so if you need to follow up you can email me at
chrismcreynolds@hotmail.com and send me samples of your files if you think that will help. Otherwise I'll try to remember to check in. I am on the reaper forum more often though, so you can look for me there with the same username.
Good luck.