Yeppers....clean the ProVari contacts

.....Inner tube and Bottom Cap Threads and spring as well.....when it's all said and done the bottom cap/spring/tube is a conductor as well as the positive pole way deep inside
I use an Electrical Contact Cleaner.....it's an Aerosol ..... just spray your all of contact points (including threads) and the inner tube....wipe and voila.....better conductivity. Don't worry if you flood the positive pole a bit, just invert it and the stuff will evaporate in like under a minute. As far as battery life.....hmmmmm Clueless
A product similar to this can be found in auto part stores in Auz
CRC QD Electrical Contact Cleaner Aerosol : Amazon.com : Automotive