Sharp microwave 1200 watts keypad showing

Not a complete answer, but may help describe problem: Our R-510B should be the same except for color, and for several years it has intermittently messed up its display. The left side two segments on the units digit won't light up. So a digit 8, without the two vertical bars on the left, comes out as a letter E reversed left to right. Any digit that uses the two left segments (traditionally labelled segments E and F when talking about 7-segment displays) comes out wrong. Every thing else works fine. I can't tell if this is your problem.
This is almost surely a bad contact at the interface between the LCD display panel and the PC board: Typically there is a "squishy" conductive strip that connects them, and I expect grease has gotten in there. If so careful disassembly and cleaning with a mild solvent should fix it. Since we can live with it, and it usually fixes itself in a few weeks, I have not got around to taking it apart.
Bob Wilson