Low output from bass to amp

On my Sterling ray34 Ive had for 7 yrs with no problems. At last night-s gig I had to have my amp on 75% gain and master volume to be heard in a backline. Ive tried new batteries checked leads, pick up height all fine, no crackling to suggest loose wiring. Plugged into another amp and same problem. The VU meter needle barely moved which means low output from my bass. Mothingbwring with my amp is new l as my other MM bass plays fine through it. Any idea what could be wrong with my Sterling bass?