I believe i've already warned people NOT to purchase a step down transformer to operate at its limits 24/7. A 70W transformer is rated at its max, often OVERRATED in its specs. Coupled to a Scooba P/S that can hit as high as 41W of consumption, u are simply threading on a thin line. U'll simply be triggering the over temp thermal cutoff often (some do not even have a thermal shutoff for lower spec models). Whats worse, the supply output will not be stable at the extreme, possibly killing the Scooba P/S! Bottom line, u need at least a 100W or above step-down transformer for the Scooba!!!!!!!! For those who are contemplating of modifying the capacitors, fine if u r prepared to take the risk. There have been known cases of P/S failing after modification (& thats not immediately). Some members here can attest to that.
In short, IMO your solution now is (select 1 of them)
1) get a 240V P/S (either from local iRobot or piggyback on someone here who has purchased their Scooba locally)
2) Use a notebook power supply that can output similar specs to Scooba P/S
3) get a Scooba 110V P/S from overseas and get a better step down transformer locally.