question about amplitude

I have had both my old grand seiko in various watch shops both here and in Bangkok to be timed on the machines that do such things. Many of the operators of the machines report back that both watches are running close to spec but exhibit very low amplitude. Does this mean the balance wheel spring is week or is it a characteristic of the hi beat movement?
one is a 1970 manual wind 4522-7010 date only the other a day date 6146-8000 made in 1969