Sainsbury's has said it has found the fault which caused a coffee machine to explode at one of its stores, injuring several people.
Six people were taken to hospital when an Elektra machine exploded at the Kingsmead Centre in Farnborough.
Sainsbury's turned off its 158 Elektra machines after the blast on Tuesday.
The chain said a design change in 2009 was probably behind a fault with the relief valve and it will reinstate its older models at 126 stores on Thursday.
Elektra said the problem had not been encountered before, despite thousands of the machines being made.
A Sainsbury's spokeswoman said the incident happened when the "boiler" within the coffee machine failed due to over-pressurisation.
It was caused by a failure of the pressure relief valve to operate, she added.
Heat continued to be supplied to the unit, causing it to malfunction.
The spokeswoman added: "The supplier of the machines has confirmed that in 2009 a design amendment was made to the machine that could potentially allow this type of failure, and that the original design of equipment could not fail in the same way.
"Thirty-two of our stores have the new design and these machines will remain out of service.
"The environmental health officer has agreed that the machines in the remaining 126 stores, which are of the original design, are safe to use and can be brought back into service."
Elektra said it had a team of specialists looking at the offending machine and it would await their conclusions before deciding whether to recall any of its products.
In a statement the firm added: "Elektra has produced high quality Espresso coffee machines since 1947.
"We export machines all over the world and the products have been tested... and have never been involved in an accident."
The Kingsmead Centre store was evacuated after the blast but later reopened.
Most of those hurt suffered only minor injuries. Five of those taken to Frimley Park Hospital in Surrey were later discharged, although one person is still receiving treatment.