Posting after I should have gone to bed after a bibulous evening was a mistake. Thanks Barrie for reminding me about Emcoshop re spares availability: I should have checked before posting. A bit of detective work, cross-checking numbers and availability between ProMachine Tools (www.emcomachinetools.co.uk) and Emcoshop reveals the following:
A5A 020 011 Saddle (A5A 050 020 appears to be the cross-slide)
A5A 021 010 Cross slide feedscrew bearing / mounting plate
A5A 000 091 Longitudinal leadscrew nut (adjustable)
Above available from Emcoshop
A5A 020 060 Cross-slide nut (adjustable)
Above apparently not available from Emcoshop, but is available from ProMachine Tools, who can also provide A5A 000 091
Also needed would be A5A 020 050, the adjuster / retaining nut for the cross-slide nut, not listed by either supplier, but could be made easily enough. As expected, the prices are depressing. Hope this helps.