Greg made a good point about checking for crosstalk interference...(it is possible anytime 2 separate units are running sonar at the same time...their beams can overlap and read each other's stuff)...so check this first as it would be easy to check...
You'll probably need to call HB with your serial number to get the info of the original software version...because I don't think Greg has access to the serial numbers in the database....(he knows the software versions but probably not the serial number units that they were loaded with)...
HB may also give you access to the software version...but if not...Greg can get the actual version download for you...(once we know what the version number is)...
You may actually do what I do for the time being....load 6.610 for use with any new accessory....then reload your older "Stable" version for image study and such....
Loading and reloading software versions is not hard...and usually not dangerous...if you follow the steps correctly...(I've been known to load and reload 3-4 times in a day depending on what I'm fishing or experimenting with)...
Rickie