This might be a hard exact item to replace, but look at the old capacitor and write down any information on it- uF capacity should be written on the old capacitor. These are metal body, electrolytic caps, and so an equivalent cap, rated the same, will work, although not be an exact fit, so you will have to jury rig it (improvise).
Here are typical specs on a cap:
http://www.capacitorindustries.com/capacitors/microwave-capacitors/sph85/default.html
Here are some caps on Ebay, and a lot of shippers are international. Here is the page:
http://shop.ebay.com/i.html?_nkw=microwave+capacitor
If you cannot find what you're looking for on Ebay, contact the following vendor:
http://www.rell.com/content/english/aboutus/Pages/Supplier.aspx
If you explain your dilemma, they might be able to suggest a replacement part.
Good luck, hope this helps, and thanks for using FixYa.