I have an old pair of welgo WPD-813 pedals, the right one is fine, but the left one seems to "grind" when i turn it, is this common or are the pedals fubar? when i remov eteh rubber seal the grinding seems to decrease. But still some resistance.
Can you get at the bearings when you remove that rubber seal?
In theory bearings should be greased, rather than oiled, but sometimes you can get a bit more life out of them by dribbling a bit of oil through them to float away any grit.
If the 'orange' emerged from the bearings, then I'd say they've had water in them and are probably fnyurkered! Pedals should smoothly spin when impelled to do so, not grind, clatter, squeak or any other variant of. WIll need at least a strip, inspect & grease, at most new balls-bearings, at worst new pedals.