Hi guys, Firstly, apologies for my "purge tower" description but you obviously understood what I meant, I'll just decribe it as tower from now on. Thanks for the responses. Whatever is giving it's not the bedplate. I have two Geeetech A10M's (you're right, cheap compare to a S5 but trying to find a decent dual colour printer sub £500 isn't easy, one is a standard stick-one sheet that comes with the unit, the other is a magnetic bed with a PEI plate, on only one occasion did the PEI plate move, practically ripped the plate off the magnet. I'm not joking about the tower not budging, it's rock solid. Especially on the stick on bed plate. I don't know what Geeetech use but my prints (and tower) are so well adhered I have to use a craft knife blade to get them off the bed (before your ask, no my Z offset isn't too low, even after the bed has cooled back to ambient temperature). I used to have issues with the towers knocking over but I increased the size to about 35 diameter and put a brim on them and haven't had much of a problem with that since. As for retraction I've turned it off, a peculiarity of the A10M is if your filament is retracted, the other side fills the gap and just causes jams as the two are so close to the nozzle.
I know exactly what you mean about getting blobs, I had a CR-X until it died and this used to leave a length of filament on the tower about a millimeter in diameter and about 5mm long on every swap, almost looked like a sonic the hedgehog but these are definite round blobs about 6-7mm spherical diameter. I've no video but I have attached a 3mf file if it helps First attempt failed but would let me delete it so tried again so there may be two attached).
GA_R3_14th Silver Dock Base.3mf
Dock Base Apr24.3mf