Just thought I would update you (and anyone else who might be interested) - I bought these the other day off Amazon and they work very well. The bayonet fitting did not require any adjustments and the light is so much better.
[h=1]
Bonlux 2-Packs 220V Ba15d LED 4W Sewing Machine Bayonet Bulb Warm White 3000K Double Connect Ba15d SBC LED Bulb 35W Halogen Replacement (4 Watt, Warm White) [/h]