Thanks for the advice guys
Can I just mention though, some folks suggested Quik Chip and I did buy some Quik Chip but I find it next to useless when the QFP has a heatsink pad underneath it, which unfortunately seems to be most of the time, from my experience!
OK so following various parts of the above replies... here is how I did it and some pics. Hopefully this quick description may help others who read this
I first de-soldered the power jack socket and the optical audio socket . I did this with my soldering iron, first applying some 60-40 solder to all the pins, then using desolder braid dipped in the flux that you can see in the pic, then once I removed as as much solder as I could I heated the pin side of the pcb with my hot air station and pulled the sockets from the component side with long nose pliers. A quick clean using a bit more desolder braid and job done (see pic 1.) I am not sure what this flux is. It is hard and comes in a tin and I have to melt it first with my soldering iron tip before i can dip the braid in it. I says 'Pasta Lutovania' on the tin and at first I thought that must mean it comes from Lithuania
Next I put the kapton tape around the QFN to be removed (pic 2)
Then I de-soldered the QFN with the hot air station, having put some Topnik liquid flux on it first.. I think I may have got the heat set too high as the kapton melted or curled up a bit. It was set to 420C on my cheapo 858D. I angled the hot air from vertical a bit so it was blowing a little towards the empty area of the board where i desoldered the sockets. Once I removed the QFN device with tweezers I let it cool down and removed the kapton then cleaned the area with Isopropyl Alcohol and a cotton wool bud. Using a jewelers loop for a close up look I found the QFN had de-soldered quite nicely (I used a bit more flux and solder braid to clean the pads) but noticed I had accidentally un-soldered and moved a capacitor (circled in the attached pic) even though it was under the kapton.
I then inserted a knife blade between the two capacitors and used my soldering iron to first apply a bit of 60-40 solder to each end of the mis-aligned capacitor, then put the soldering iron bit sideways so I could heat both ends of the cap at the same time and used the knife blade to push the two caps apart.
This did not work perfectly to plan as the cap moved suddenly and moved a bit too far.
So I then used the same technique of heating both ends of the cap at the same time and used tweezers to reposition the cap, then de-solder braid and flux to clean excess solder from the ends of the cap.. (pic 4)
That all looked good so I cleaned everything with isopropyl again and examined again with the jewellers loop. The last pics show the PCB and the QFN after removal.
Both the device and the PCB were undamaged
I think I did a pretty decent job???
Kit used
ZD-915 solder station
Atten 858D hot air station
8 diopter (3.25x magnification) illuminated bench magnifier
x10 jewellers loop
Flux Paste, Topnik Flus, Flux pen, 60-40 lead solder, desolder braid, isopropyl alcohol
You may notice I use the top off an old satellite receiver when working with hot air so it does not char my workbench
I just need to order a replacement part (get a pack of 10 from aliexpress for about €4) and solder that back in place. I will put 60-40 on all the pads and try to get the hot air temperature a bit lower so it does not quite melt the lead free solder on other components. I find from experience that method seems to work quite well.