Spin-on or canister filter? I know the M103 has a spin-on.
If the crud fell into the outer part, no problem, the filter will catch it all. Oil goes from oustide to inside.
If it fell into the hole the clean oil goes down, it will get flushed into the engine.
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!