1.4 340 Carb query

My `88 340GL was a bit tricky to start and a bit rough the other day - I found that the top cover of the carb was loose - this was the 1st thing I checked after the choke actually, having come across this problem many times with my previous car. Do these engines always shake their carbs to bits?

Reminds me of a potentially dangerous breakdown we had a few years ago when the big plug near the fuel intake (Weber carb)fell out on the motorway, spraying the hot engine with fuel. An hour with the AA man looking for a scrapper with the same carb and we were back on the road, but it could have been nasty.....

Anyway my query is:

Has anyone come across this before and have they found a long term solution. Perhaps spring washers or Loctite ( I`m not too keen on this as with my old car I was always having to dismantle and clean the carb and don`t really want any extra gunge in there)

Any suggestions appreciated

Will Plummer