79 KZ400B Balancer Timing - something I noted on reassembly

hello all, am reassembling the bottom end on my 79 KZ400B project and all is progressing well. cases are now spotless, as is the complete trans and crank, and installation of them went very well. have a clymer's, kz400 service manual, this site, and have watched some youtube vids also. i take the time the read everything i can get my hands on before proceding to the next step and this has served me well so far. the trans shifts nicely thru the gears, crank is in place, and i've set the balancer timing according to the reference material i have on hand. and here's the question,

prior to installing the balancer i place a small dab of grease between the two middle, plated sprockets to enable me to see them during placement on the crank sprocket.

after i place the front and rear plated chain links on their respective balancer sprocket marks, turn the crank such that the oiler hole is centered on the case with the crank counterweights pointing up, i install the balancer. i make sure to keep the balancer chain taut between the front/rear balancers during installation, checking the placement of all markings relative to the plated links.

the plated links are matched to the punch marks on the front and rear balancers, the crank oil holes are centered on the case with the counterweight lobes pointing up, the center link between the two plated links was placed on the appropriate sprocket tooth, and the marks cast into the balancer holder lineup with the balancer punch marks. all is well until i rotate the crank and note that the plated links migrate from their initial positions. i've rotated the crank by hand for quite a while, both sprocket punch marks still line up with the marks cast into the holder and the crankshaft oil hole is still centered on the case. it appears that the timing of the balancer relative to the crank is still holding but am unsure why the plated links are moving off their initial setting. and does it matter if they do?

the bike appears to have been maintained well, as evidenced by the condition of the gearing, crank journals (needed just a slight buffing w/1500 sandpaper) and camchain guide. i plastigauge'd the crank journals and noted clearance of .051(midway between the spec of .034 - .076).

appreciate your comments, and thx.
bob p

checking a little further i found that the plated links migrate one link on the balancer sprocket every three revolutions of the crankshaft. turning the crank 21 full revolutions move the plated sprockets back to their original position. the balancer sprockets have 21 teeth. with a chain drive, i knew that the balancer position relative to crank position couldn't change,i was just wondering about the link position.