May have found a fault in my bass keeping tune - the tuners were just a tad loose in the mounting screws, so after a tightening (and a reintonation on one string!), it sounds clearly truer in tone. The neck also has the slightest amount of bow too - I'll get to that too.
Nonetheless, the OEM tuners weigh 79 grams each - that's about 3/4 of a pound for the four of them. So, I've ordered Hipshot Ultralite USA tuners to eliminate any further issues and hoepfully cure the little neck dive I deal with...