Thanks. I have now done further tests:

Using a DVM (which averages readings over a 1/2 second or so and accordingly does not show spikes, which might trigger problems) and with 7" legs and wheels weighing about 4.4 ounces

On 4 cells 4.8volts

Operating current for two legs - up to 0.8 amps.

Voltage at battery drops to 4.8v, presumably less at the units.

Stall one or the other - up to 2 Amps for a few seconds, while buzzing followed by tripping off.

Voltage drops to 4.2 volts, enough to trigger throttle failsafe to slow and perhaps stop coded signals getting through.

One wheel or both will fail to operate about 1 time in 5.

Simply touching a small screw - no force, just touch - on one of the mounting flanges will trigger a down/up cycle - sometimes but not always.

The margin between just about operating normally and tripping off is TINY - slightest touch with a finger against a wheel will cause it to trip, so nothing whatever in reserve.

On the worst unit there are clearly 3 tight spots along the movement, most logically due to thread imperfections.


5 Cell 6 volts

Contrary to suggestions, more voltage does not prevent these problems.


As things stand I am undeciced about whether to return and demand my money back as unfit for purpose, or to hope these are just bad units and replacements might work or strip out the badly designs parts and use the basics using servo operation.


I note that the guarantee - not visible until the box has been opened of course - says it is limited to repair or replacement. I do not know whether they can get away with that under US law, but they certainly can not under British law which requires that products do what they are supposed to do, for a reaonable time, and are fit for purpose.


On balance at present I think that these units are so badly designed as to be unfit for purpose, that replacements would also be and that I should stop wasting time and money on them