7 segment LED woes Akai AX-80

Been working on a AX80 I picked up a bit ago- the usual issues with broken button board bridges and bad key contacts. Today something new popped up- the top segment of all of the 7 segment LED displays and the Preset LED will flicker on and off and often stay lit. Sound data is fine and all the button functions work, but it’s driving me nuts. Checked voltage to the op board and it’s good, reflowed the NAND gate chips ahead of the displays… now I’m stumped. Maybe it’s the (programed) Keyboard scanner / display multiplexer chip on the CPU board? Anyone run across anything like this before and could offer a few helpful hints? Pic here shows A1 bank, note the top segments stuck on. Thanks in advance!image

Why don’t you try to solve again all the connectors of the welds tend to overflow and it looks like they are in perfect condition but it’s not so maybe that’s the problem