JVC has a special repair programme in operation that gives a FREE repair on the lens cap fault provided its listed in a certain range of models (which yours as a GR-D70 is!) it should be pointed out that to obtain this repair you must have the original purchase receipt.
Go onto the JVC web site of wherever you are located country wise, and it should be listed in the support section, I am unable to send a direct link (with added info) as you have restricted your e-mail address.
Speed is of the essence as the offer ends at the end of this month. (30th June 2008)