Grumman Tech Support should not be a problem. The type certificate holder True Flight Aerospace is there to help. If anyone has problems contacting them PM me and I'm happy to help out. Parts support for all the usual maintenance items should also not be a problem with the European agent for the main US Grumman parts supplier based here in the UK with a good spares stock holding.
There is a STC acceptable to EASA for a high compression modification that
greatly improves the take off and climb performance of the AA5A's.
Most AA5A's on the UK register do not have the purple glue as they were imported after 1977, but having said that if a plane hasn't shown signs of delamination by now it probably doesn't have a problem. Our group owned a 1976 AA5B with the purple glue and has never had a problem, but it did spend a good number of years in the dry states of the US before importing to the UK.
There is a Service Kit SK125A which covers the repair of delmination with flush rivets, but having said that I have seen some repairs that have been carried out that do not comply with the SK that look more like a riveted Piper or Cessna.
If you search the owners group web site
AYA - Welcome to the AYA you should find a wealth of infomation including a list of suppliers.