Bah-barp, wrong! You can't tell with R34 ones just by using a multimeter, they pretty much fail under operating temp, and the have an isolated firing circuit inside which will not tell you anything by measuring resistance.
Almost all R34's have the packs shit themselves, just replace them and avoid the agony and time looking into a problem that is well know and can't be fixed by silicone, tape, araldite or gypsy tears!