The drive on my Honda HR2160 is slipping ?

Hi, I have a 1992 Honda been going brilliantly but now the drive has started to slip (rear roller type) and its very hard work . Local repair shop says gearbox is £200. How can I remove it as another web site says it could be overhauled for £120. Alternativel theer are lots of mowers advertised where the body has had it but the drive is fine. It looks as if the rollers must be removed, does it then easily disconnect? Any advice gratefully received