When did they replace a 2610 with a 2720, must have been some years
ago
If you're hoping to recover the mapping data from the 2610 to use on the 2720 I'm afraid that you're out of luck. Firstly the img file is for use on the GPS not in Mapsource, I don't thing that Mapsource can utilise that format. Additionally the 2610 mapping will be locked to the GPS it came from and wouldn't work on the 2720 even if you could get it on there. The 2610 ran off pre NT mapping, the 2720 was one of the first to use the NT mapping which is still in use on Zumos etc. The 2720 will actually work with pre NT mapping but some of the features will be missing.
Did the 2720 come with any mapping installed? Assuming if it was supplied from Garmin you have a myGarmin on-line account with this GPS registered? If this is the case then, IMHO, the easiest way to go forward would be to buy a lifetime mapping update (Handtec or Pentagon GPS for a smidge over £50). Once this is set-up you can then download the latest mapping to both the 2720 and your PC. This is made slightly more complicated by the fact that the whole of Europe no longer fits onto the internal memory of the 2720. You can select to load a chunk of Europe that suits you as part of the download process, the regions on offer don't always suit though. The alternative is save to your PC and create your own custom region in Mapsource.
Creating a custom mapping region for a 2720 is complicated further by the fact that you can't access the internal memory directly to replace the primary mapping file as you can with later Garmins (or the 2610 via the CF card). You can write it to the unit via USB from Mapsource but that just creates a supplementary mapping file (gmapsupp.img) that will be put alongside the primary mapping file (gmapprom.img) in the limited memory. The ideal solution is to replace the primary mapping file with a new gmapprom.img. With the 2720 this is a somewhat laborious task involving command line stuff that you might not be comfortable with. If you want to go down this route ask and I will provide more info.
Of course, if you're on a real budget you might want to consider using
openstreetmap. This works very well, tested a few weeks ago having downloaded Georgia. See screen grabs from Mapsourec below:
Garmin basemap - Tbilisi, Georgia
Openstreetmap (same view as above)
Openstreetmap - zoomed in showing POIs
Openstreetmap - route in Georgia
I loaded the mapping and route onto my Nuvi 765T and both worked as expected. Very impressed, who needs Garmin mapping updates
Well I have lifetime on the Nuvi. NB sea doesn't show as blue with Openstreetmap data.
When I get some time I might run a comparison for Europe on my 2720 which only has 2011 mapping and no lifetime update. It's possible that the Openstreetmap data is slimmer than the mapping from Garmin as it will lack stuff like 3D buildings and Lane assist which the 2720 can't use anyway. This means that all of Europe might fit on...
