Hi Rod, having just bought a used Alpha 5 (12 December 2006)I did a lot of homework. There is a small nylon gear that fails on these players and stops the drawer working. It costs around the £10 mark. In my recent experience, Arcam are very helpful in sourcing parts - though you'll need to hurry to get one of these I think as the complete Philips transports are no longer available.
Alternatively, some folks on eBay sell them - check this one: http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&ih=017&sspagename=STRK%3AMEWA%3AIT&viewitem=&item=270057029994&rd=1&rd=1
I wish I had advice on how to fit this. My guess if you've ever spent time under the lid of a CD player or tape deck, you could figure this one out.
Good luck - I guess I'll need to do this one day soon.
Chris Mann, December 2006