Tim Downie wrote:
I know these things aren't normally worth attempting to repair but
because TiVo have just about giving up supporting new Freeview boxes for
the TiVo, I'd like to repair it if possible.

Actually, that's wrong, they haven't given up. :-)

The TiVo remote control database (and suggestions etc..) is still in
active support for newly released set-top boxes in DTT, Satellite and Cable.

For really new set top boxes, and with access to a Philips Pronto
learning remote, the IR commands of the original remote control can be
captured and sent to TiVo Inc.

http://www.garysargent.co.uk/tivo/stb-unsupported.htm

There is a lot of assistance on the UK section TiVo Community. We are a
helpful bunch compared to Sky who ru(i)n the phone line support.

Good luck with the cap repair!

--
Adrian C