I have a 2247A myself, excellent GP scope.
One of the first recommended things to do I was told is replace all the rectifier diodes in the A18 LV power supply that have ZM or ZS markings on them as they are well known to get leaky after "some time" (quoting the very knowledgeable person that sent me this recommendation). Replace these diodes with MUR160 600V 1Amp, you easily get them at Mouser, Digikey, etc. On my scope all of them had either of the above suspect markings, so just to be safe I replaced all of them. Whole procedure takes maybe an hour or two, your mileage may vary.
Of course for an instrument this age, needless to mention to also check filter caps, specially if you see higher than normal ripple on any of the supply rails.
Suspect diodes are Tek PN 152-0400-00 (total 17 diodes) with alternate PN given as MB2501. These are the on-board part locator numbers:
Hope that helps.