I pulled my FE160 off the shelf. I haven't yet bothered blowing off the dust. This is only about the 3rd time I've played with it in decades. I have no recollection of the calibration procedure, but I do recall the last time I tried it, the switches needed contact cleaner for the meter to be usable. When checking zero with no input, switch thru all the ranges. Any erratic readings may indicate switch cleaning is needed.
I checked mine with 1VDC and 10VDC from my calibrator and it seems to be working accurately in the low ranges. The meter zeroes with the ZERO ADJ knob at about 1/8-inch past halfway. It can also be adjusted to center-zero on all ranges. On the 1VDC range, with ZERO ADJ fully CW, it reads about 0.65V. My best guess is this is a compromise setting I made the last time I calibrated it. It's been ages since I did this, so I can't say what I did. Since this is an offset adjustment, I don't think it is affecting accuracy, as long as zero can be achieved.
In the manual, it's clear the DC Balance procedure should state that the ZERO ADJ knob be fully CW when setting 0.7V on the 1VDC range. I consider the low reading on mine to be tolerable on an old analog instrument.
I would suggest making an adjustment that allows the zero and center-zero settings to be achieved without also achieving the 0.7V. It may be necessary to have the ZERO ADJ knob not be halfway. If zero can be reached, it's not that important where the knob is.