how to mesure the load on a battery?

I have no clue about this kind of stuff, but maybe someone here can help me.

I have a 4.8 volt NICD battery pack 1700mah
there are 8 total devices connected (servos etc.)

a brand new battery used to last for 5-6 flights when in use.
now the battery only lasts for 1/2 that time.
I already tried a new battery pack and no changes, so I'm sure one of the devices is bad - drawing to much power.
without guessing, how can I find out witch one?
I have a volt meter (cen-tech P30756 https://www.universal-radio.com/catalog/meters/1496.html) and though maybe to connect it to my battery and see the draw and then disconnect one device after the other to find the one that draws the most.
what setting do I have to use and can this be done?

please be gentle with the hi-tech words you use.

thanks for any help.

if you have an ampermeter you sould connect it in series to each one and see who drains the most current, and if it's over the rated current for this device

Found it, that was my problem, I kept connect it in parallel which was wrong.
thanks