Removing and refitting shouldn't be a problem, but you will need some jeweller's screwdrivers and a pair of small needle-nose pliers. The ideal is a proper cartridge spanner, such the one in this set
but a pair of very small needle-nose pliers, used with care, will do just as well.
Fit the stylus guards to both cartridges, and then remove the wires from the rear of the cartridges by gently pulling the metal tubular tags off the pins on the rear of the cartridge.
You can see what i mean by the pins in this pic
- the 'plugs' on the end of the tonearm wires are little metal sleeves that slip over the pins.
When you've pulled off the first wire, 1) breathe a sigh of relief and 2) check whether the cartridge has colour-coded markings to show which wire connects to which pin. If not, make a quick diagram of the back view of the cartridge, and which colour is on which pin.
That done, pull off the rest of the wires, then undo the bolts holding the cartridges in place, and remove cartridges from the arms.
Reconnect the wires on each arm to the 'new' cartridge, then mount the cartridges loosely in the slots on the headshell of the arm.
The next bit is fairly simple if you have the original alignment protractors supplied with the turntables - if not, you can download a protractor here
, print it out (making sure it prints at 100% by meauring the reference distance printed on it), and use it to line up your cartridges. The hole goes over the spindle on the turntable, and the idea is to set the cartridge so it sits square with the grids on the protractor at both points when the stylus it at the centre of the cross.
And yes, it is fiddly - no reflection on you, but I'd try the Stupid Protractors as a starting point!
When you're happy, tighten the nuts and bolts up firmly but gently.
Now adjust the counterweight on the back of the arm so the arm floats parallel with the plinth, then dial in the amount of downforce the cartridge specification requires. On some arms this is easy, as a calibrated collar can be zeroed when you have the arm floating, and then tracking force dialled in using a scale - for others you'll need a balance such as the Ortofon one mentioned in the original post.
You'll also need to set the anti-skating/bias to match the downforce setting - some arms do this with a dial, others with a weight on a string. Again refer to the arm manual.
The final niceties are the adjustment of the vertical tracking angle - or VTA - if the arm allows this. The idea is to get the arm level (or at the VTA suggested in the cartridge specification), and this is usually done by releasing some screws and moving the whole arm pillar up and down so the bearing height changes and thus the arm is set to the right angle. Sometimes the arm pillar is then just clamped back into position, but on some arms wafer-thin shims - 'just one waffer-thin shim, M'sieur?' - are used to adjust the height.
Frankly at this level of expertise I wouldn't bother - the tracking force and alignment are much more important, and I think by now your head may be spinning quite enough already.
And that's what I did on my lunch-break - how was yours?