I had to jury rig a switch in my first tube mod, moving parts like buttons will all fail eventually, the spring will break or go too soft. If you can tear it down as far as you are able and shine a very bright light inside to see if there is any hope of self repair. Otherwise I fear the only options are to keep using it as is until it fails completely or use another mod, unless the following help...
Doing a little google fu this is the twitter for the GVM Groove:
GoodVaporMods (@GoodVaporMods) | Twitter
The homepage is not working but is/was here
http://goodvapormods.com/
Some posts here in ECF mentioned a STEVE, possibly the maker of the mod.
This site used to carry the mod, they might have contact information for the maker:
Welcome to Vermillion River Premium E-Juice I found that site in this ecf thread:
The New Store is Open.
Old Guss is a forum supplier mentioned in the thread above:
Old Guss
This is the ecf page for the groove and
@TroopX apparently has a buddy STEVE that made the Groove:
GVM Groove!
Hope this helps.