Not justifying quality issues here, but there are big big supply chain problems in China at the moment in a number of areas. Falling demand for goods in general has lead to higher costs, loss of skilled labour, and a number of specialist manufacturers of the component parts going bust. (to name but only a few of the multitude of issues!) Hornby, for example, had a number of set back throughout the past 2 years as a direct result of this uncertain market, so I would assume the Paddy Murphy is small fish in the grand scheme of things. It's catch 22 for everyone: No Paddy Murphy, no rtr models of the Irish scene. With Paddy Murphy, but poor, unreliable pool of suppliers in China, probably gonna get some hic-ups along the way. I have been sourcing product from China for many years and with the best of intentions it is so hit and miss. When problems do occur it's very hard to remedy. Bond and insurance normally only cover transit. So you try and choose a supplier with the best reputation. But from time to time you are let down, and it is very infuriating!
So look, the solution as a 'customer' is quite simple. If you have bought these Mk2s and they are not up to scratch, return them to your supplier/shop and get a refund. Simple. You'll be disappointed but that's just how it is. Ensure you explain to the retailer why you are unhappy with the product so he can feed back to Paddy.
If you have bought them and are unhappy, but in a kind of 'I can live with it' way, then again make sure that you go back to your retailer and explain how you feel. Ask for a discount on your next purchase for example.
If you are over-the-moon happy with your Mk2s and they are not showing any flaws, then let your retailer know this too! Sometimes we forget to give praise when it's due.
The fact of the matter is this. Unfortunately there appears to be flaws. It's highly unlikely that they are going back to China. If after a month or 2 have passed and Paddy Murphy is looking at a pile of unsold stock or a load of returns from Retailers then he will have to take action of some sort. This would probably involve negotiating some kind of compensation or reduced final bill from his manufacturer, which in turn might lead to a reduction of the retail price, with the product being sold 'as is'. Disappointing all round, and will certainly put a question mark on future releases.