Just to give an update on this issue;
So I ordered the U34 chip from ebay (from a seller in Italy) - I managed to remove the chip with a soldering iron without ripping the pads (I don't have access to Hot Air Station) by flooding the chips pins with solder, wicking up the solder and slowly lifting each pin. I replaced the chip but the behaviour still persisted with up and left not working on the joystick.
So in my frustration I attempted to repeat the process as I received 5 chips from Italy but this time I ripped about half the pads the chip sat on - I attempted to retrace these and a put a new U34 back on - at this point it was a total mess and now the mouse only half worked and only fire worked.
So I had to send off my Amiga 600 to Luke at Retro Six for repair (Cost me £60) - who I can't recommend enough (Guys is a Wizard with this stuff!)
He posted a tik tok video of the repair on the retro six tick tok page (also his facebook page) of him repairing my mess.
He also mentioned to me that the resistor on the MV1 line (68R termination resistors) had burned out which he said is starting to be very common.
Hope this helps someone!
Thanks for the help from the previous people who replied.