This web site has some good info on robots, and also some hints for repairing the Diagnostic Dolphin: http://www.i-love-my-aquabot-automat...com/index.html

I can give you a users' report on the Dolphin. We bought one about 5 or 6 years ago. For some time all was well; it climbed the walls, it vacuumed, it dusted, it polished. However, about 2 years after we bought it the strain relief on the power supply gave way. I opened the power supply (the horror!) and determined that replacing the plastic fitting wouldn't be beyond my abilities, if I had the fitting. Maytronics, the Dolphin's momma, refused to sell me the fitting, told me I should send the ENTIRE unit to them, at my expense, of course. They said they'd update software, etc.

About $60 shipping each way, my dime both ways, plus about $150 for Maytronics' expertise the Dolphin returned with the strain relief fixed, plus a float added to the supply cord about 2 feet from the robot. This, I was told, was to insure that Dolph wouldn't trip over the cord. Problem is, now even with the floats on the handle removed Dolph's wall climbing is but a shadow of its former self.

Early this summer I noticed that the flexible clear plastic cover over the power supply switch was deteriorating. An extensive net search located one, with a $25 minimum order for a $3 part. I called the local Diagnostic distributor in the Atlanta area, and was told that the design of the cover had been changed, so shipping the power supply might be necessary. After a little whining and pouting on my part, they located a cover (on someone's desk?) and sent it to me gratis.

At one point Dolph had thrown a tread. I used the above site and took off the side plates and removed .... a plastic shard from one of those really flimsy little pots that bedding plants come in. The plastic was barely thicker than 30 pound paper! Nasty job undoing Dolph, I left some blood behind, and I've done car clutch jobs, etc.

Long story short, I doubt we'd buy another Dolphin. YMMV, of course.