Yes, as I say I'm a novice when it comes to using my effects loop as I have previously only gone into the front of my amps. The Vh4 is a bit of a complex beast, having an effects loop for every channel, plus 2 additional series and parallel loops and midi switching on top of that. In comparison on my EVH, when I was using Helix patches (which I generally only deployed to do something the 5150 just could never do, like an Eric Johnson tone) I just made presets on the Helix, plugged it into the front of the 5150 on channel 1 and set the EQ on the 5150 flat.
Funnily enough, rd2rk's method worked for wiring up the Helix FX unit (thanks for that!) but the Helix Floor, still no luck. It still worked as before with my custom presets running into my 5150, but as I will probably move the 5150 to a practice space, it seems pointless to keep the Helix. I won't be using the amp / cab blocks, I don't use it as a recording interface and the effects aren't good enough in themselves to warrant holding on it - I'd rather just go back to a full suite of individual pedals at this point. The Helix has now been subject to a factory reset, is photographed, boxed and ready to go on sale. I'll probably use the HX FX as an interim and then sell that once I've got a few more bits and pieces to get my full band pedalboard back together.
I thought yesterday that I'd keep it simple, if all I need if reverb then I could just plug in an old TC Electronics Hall of Fame 2, despite me not being overly enamoured with the sounds on it, but it made a sort of digital noise before cutting out, just my luck! Not a battery issue as I run everything from a Voodoo Labs Pedal Power 2, so I guess it just became decrepit in storage - I hadn't used it in years. Oh well. The delve into the storage did yield a few nice finds I'd forgotten about, a TC Polytune, a Digitech Whammy 4, a Boss chorus and a few other bits, so I'm already a good part of the way along to where I need to be for band and jams. For home use, a nice reverb will suffice and perhaps a bit of delay.
Alas, it seems my journey with Line 6 products is coming to an end. I did think after owning a PodXT around 2005 that I'd never come back to the brand, but the Helix line is pretty good at which it sets out to do. it served a purpose, for a time, but I think that time has passed. Thanks for all the assistance from everyone who responded!