In between a host of domestic chores, I managed a wee update to the suspension; fitting the return rollers, in fact. Before that, I added a plastic stop (sort of travel limit stop- indicated by red arrow) to each of the 10 swing arms. This would prevent the arm going dropping down beyond the 6 o'clock position. (Going anticlockwise from 6.30, say) In fact, given the position of the retaining spring, in certain circumstances (without a restraining stop in the way), the arm could swing in the opposite direction of travel to the intended one- thus fouling the adjacent wheel.
Click to ENLARGE these images.

- Arm travel limiter indicated by red arrow
I finally decided that it isn't practical to fit the Taigen Pz 111 return roller assembly in its entirety. I only used the roller mounts, eventually, having drilled them out slightly to accommodate the Tiger 1 axles.
The Pz 111 axle only passes through the inner wheel of the roller (not both halves), going into the hull wall. The captive head of the axle, about which the rollers pivot, is sandwiched between the rollers in an arrangement I've never liked; especially if the two halves are not superglued together firmly- or if there's too much glue

The axle itself is only long enough to go through the outermost of the two hull walls in the
Comet. Thus,
if you want to use the full Pz 111 roller assembly, you will have to fit it
before
the lower hull sides are bonded together. Thereafter, once the hull sides are bonded together, you'll have to hope you never have to remove the roller axle for maintenance: It will be nigh on impossible.

For this reason, I opted to use the long Tiger 1 axles, which- by a happy coincidence- are a perfect fit for the Pz IV alloy rollers, and pass right though into the fighting compartment

They should be relatively easy to remove for maintenance

- Comet rollers- pic A
I pressed the Pz 111 roller mounts in using just a dab of two-party epoxy on each of the three locating lugs ('Plastic Fusion'- also suitable for metals)
Then, after a wee bit of judicious drilling on the inner wall of the hull, I fitted the Schumo alloy rollers and Tiger axles.

- Pz IV alloy return rollers and Pz 111 mounts
I then put a straight edge through the centre line of the idlers, and the rollers, and found they lined up pretty well. With lots of luck, and maybe a few washers and spacers, so will the drive sprockets and wheels, when I come to fit them next.

- Checking return roller and idler alignment.
"Get your facts first, and then you can distort them as much as you please"- Mark Twain.