I have got that part just cleaning itFree Fobco? Lucky man!
I think the wee screws are B.A. thread but I don't recall which one.
Measure the diameter and pitch carefully (verniers or micrometers and thread gauges) and have a Google for thread charts online.
If you pick up a copy of the Model Engineer or Model Engineers Workshop from a newsagents (W.H. Smith usually keep it) there are suppliers of oddball fasteners that advertise in them.
Looks like you're short of the quill lock too BTW.
G&M Tools might have some Fobco parts kicking about but they do know how to charge for them. Otherwise stick a wanted ad on here as lots of forum members have them and may be able to help out.
The quill lock that isI have got that part just cleaning it
Might be cheaper to buy another drill!Lathes.co.uk does Fobco spares, spendy mind you