Vulcan Dishlex Model 750 ECO dishwasher?

Re: Vulcan Dishlex Designer Collection 750 ECO electronic model A8577WG has wash program buttons on the front panel:
ECO Delay Rinse Fast Normal Pots Super Cancel

I have not used the dishwasher for about 4 months and now its - Fast & Normal - wash program buttons do not respond / function when I press either of these two buttons. All other wash program buttons respond / function fine.
Any suggestions to rectify / repair / replace the faulty buttons would be appreciated.