I'm close to finishing a new build of a commuter bike with Dia Compe-style ratcheting downtube shifters,but the front derailleur return spring seems stronger than the ratchet/friction system in the downtube shifters. I shift up to the larger chainring, but the derailleur pulls/slips back toward the smaller chain ring. The derailleur is an FSA Gossamer compact double and the downtube shifters are new Dia Compe-style shifters from Velo-Orange. What am I doing wrong? Thanks, all.