Thank you Glen, glad they helped, although I was a bit concerned to see your frustration with deleting mark points! The videos don't cover this, but the step-by-step guide does, if you'll excuse the unashamed plug
I have no affiliation with Tascam so if you decide to sell it, that's fine by me, but I would give it another chance. It's a complete studio in a box, so needs some time & patience to adopt and adapt your work flow - think back to your first time in the studio 'driving seat'!
The replies re. firmware and auto-punch are sound advice, but the way the unit handles markers in general may not seem intuitive, although this does not mean they are bugs - it's just 'how it works'. You have to locate *precisely* to the marker point in order for the mark button to delete it. Jogging goes down to 3ms resolution, but this is still not accurate enough (I guess the machine marks at the sample level), so you have to position the transport another way - all these options are summarised in the guide.
By the way, an alternative to punching is to overdub onto spare tracks and merge the good bits together via bouncing, muting or copy/pasting etc. These are standard techniques.
Anyway, hope you stay with it. Keep us posted.