I met this Gentleman, Benno DK7GB, recently during Hamradio in Friedrichshafen and we found that we both own one of these fabulous SE6861 radios.
Mine, I was able to score at a very decent price at a tiny hamfest. Interestingly my best hamfest bargains were found at the smaller venues, not the big ones. Anyway, all that was needed is to replace the long gone battery packs with new ones.
The new ones are 3500 mAh cells that I found on eBay (and which surprisingly really hold that capacity). They were soldered together, arranged on a piece of FR4 fiberglass board, wrapped in heatshrink tubing and attached to the bottom of the battery compartment. Power is supplied to the radio through standard 4mm sockets. The charging circuit was slightly modified by increasing the charging current to the battery to 350 mA (for a C10 charge). Charging power is supplied by an old Dell laptop power supply with an attached Mil power plug (that alone has cost almost as much as the radio)
The entire modification is fully reversible.
The radio itself is nice to work with as it is fully self contained, runs USB, LSB and CW with 20 Watt, has a lovely antenna tuner and can tune any wet string.