Its worth having a really good look at the oem parts and then making sure the new ones look to be at least as strong. I noticed alot of differences some even being pressed where the OEM were cast. I trust S4P not to sell rubbish, but these things are fickle. The dealer in Norwich did the last arms on our 169 and used aftermarket parts that they obtained. They used the original bolts. It seemed OK for 60 K afterwards but was getting rattly just as we changed it for a 319. If the bolts are not corroded or worn they should go around again. I later did struts and steeing ends and the pinch bolts were badly corroded so I changed them but that was a few years back and it cost £4 each bolt if I remember right. If the arms move without sticking and feel OK I am sure it will be fine. I think the suspension is old design, simple and therefore not very long lived. Its a trade off against the cars price I suppose.
How are the tyres? I have noticed Noop (2019 TA 4x4) has also felt twitchy recently and I think its the mud and salt as its usually planted. The winter tyres a re definitely much much better when the temperture is down to 3.5C. The weather / roads have either been wet and slimy or like today dry and dusty for a good while. Tyres these days seem to take longer to settle down. They last longer too, so its likely the compound. New tyres on our 1.2 lounge a month back have had that odd feeling as well. New tyres always go on the front for me for this very reason they cannot be relied on to match the grip of worn ones. WIth it feeling twitchy the back is NOT where I want suspect performance. Also they take the strain of braking and cornering so its sensible to put them where they work hardest when new. Next time I need tyres it will be all 4 which I prefer. I have read a lot about fitting new tyres on the rear axle and regard this as out dated, and a throw back to the days when rear wheels did the work and oversteer was the problem to be addressed. I have been told emphaitcally by several tyre suppliers to fit on the front axle. My logic to new on the front extends to wet conditions when the rear tyres with slightly less tread are running on dryer ground after the fronts have cleared a path for them. I throw tyres away at 3.5mm as the wet braking is so much worse from there down. If its August when my tyres are needed I will wait till1 November to have new ones. Having driven on worn and new tyres for so many miles I think generally if the tyres are legal and still in good shape Im making a fuss about nothing re the tread, aquaplaning aside. Having had an insurance inspector come and look at my car after someone T boned me while I was minding my own business, and seeing tehm go straight for a tread depth check before lookikng at the damage, Im inclined to err on the side of good tread. The 1.2 has also only done 100 or so miles on its new rubber and no real improvement yet. It totally justifies putting them on the front where I can feel what they are up to!!! These are 185 tyres too (wide for a Panda) so its slithering is way out of character. I hate buying tyres unless changing all 4 as the balance is always messed up. I do so few miles now its unavoidable. I shall take Ruby out and howl round a load of corners for 50 miles or so. That should sort it! I did drive an absolutely HUGE milage in years gone by, 16 tyres on my Vectra in 2 years which made Vauxhall leasing cough, so I have tried just about every make you can think of and worn them all out with some brutal driving. Two things I learned are the top brands are way way beter in terms of safety especially in bad conditions, and second you egt what you pay for in terms of better wear. Now I do very few miles Im getting tempted to try the mid range tyres as these are now so much better and wear rates are not relevant to me anymore, however stopping distances in bad conditions and resistance to aquaplaning are two things that matter. 1 extra meter to stop is a thing to tink on. When that rises to 20m how fast you drive is a mjor issue in making a choice.