CNC 6040 Controller upgrading parts

OK I am looking at replacing the Chinese components in the control box to hopefully fix an issue with my machine jumping (checked frame for alignment and all seems in order) so possibly down to some electric noise or cheap board.
Now I have researched enough to attempt install the following however I don't know which to buy and gratefully ask for assistance:
a break out board (preferably with Ethernet connector)
3 stepper controllers
screened wiring
48v power supply
my only issue is I am on a budget and when looking at breakout boards/stepper controllers they vary in price greatly (cheapest BoB I have seen is £3 with most expensive BoB short of £100) smooth steppers pricing goes higher in three digits.
my price range I am looking at for a breakout board is around £50
for stepper motors around £20 each
screened wiring I just cant get my head round all the types I keep ending up looking at audio cables with 4 screened wires.
The screen shots are of my currant control box

Copper braided CY cable is what you want. Doesn't need to be big for the motors, but if the problem is happening without the spindle running I very much doubt noise is the problem. Just change one thing at a time, try the PSU first as that was what caused the same issue for me and they're not all that dear. Also try it with a different PC as that can cause the issue if it doesn't run fast and smooth.

The cluster bomb approach could very well end up costing you a lot more than it needs to for little/no real benefit.

I'm with Snapper on this one - take a breath and think logically what is going on before a blind replace-and-see that, only at best will break-even over the cost of replacing the correct item, and at worst will see you throw your money away.

I'd also agree - if you are to replace the cabling to the steppers - 0.5mm2 csa CY cable is the way to go, with the screen grounded at the controller end. Simply because of geography I tend to use "CB17088" order code from CPC (part of the Farnell group) - it's 0.75mm2 (which is better, but more £££) as the only spec that they sell by the metre (0.89/m + vat). Don't use screened audio cable - it's unlikely to be specced to carry the current you're talking about with steppers which will manifest itself with lower mechanical energy out of the stepper.

That photo of your controller box - there's a big ferrite across the spindle supply - that's to suppress any noise induced by the spindle - it should help things - which makes me wonder what your problem truly is - you mention missed steps, but that's a little vague to try to isolate the problem and offer sensible advice. You miss steps how, and when, and as Snapper queries - whether its related to spindle noise. Have you tried, for example, touching a fine bit against the bed (or sacrificial bed) at work coords {0,0,0}, raising Z, then air-cutting a complex/fast outline, then returning to {0,0,0} to verify the position of the spindle, with both spindle on, and spindle disconnected?, that'd tell you immediately if the problem is with noise before spending money.

Do you lose steps on one axis or more? Do you lose steps in one location on the machine (mechanical), or anywhere (possibly more electrical)?

You ask about alternatives to (a) stepper controllers, (b) BoB (pref. ethernet), (c) screened wiring, (d) 48v power supply.

(a) - why?, does the controller you have not work? - for a £20 replacement you're unlikely to get anything substantially better than the TB6560 solution on your board already. Unless you definitely need (/want) to replace the parallel-port drive with something else - and you'll have seen there that basically takes you on a £100/ethernet board + 3x£20 stepper controller journey of £160. Which might not cure your problem.
(b) Tied in with reply to (a). What's the problem with the BoB now?, missed steps?, then why do you think a replacement will resolve that? I *did* go with the cheap ethernet BoB/motion controller replacement at around £100 (NVEM controller) - and have some experience - would I do the same again?, possibly not - but I understand some of the limitations with them.
(c) Cable - depends on what you have at the moment - I'm assuming you're talking from the controller to the machine?, it could help, and the advice above - CY cable holds true, but I'm not convinced yet that is your problem. Although cheap to try.
(d) 48V PSU - affects the performance of the router at speed. Try a lower feed rate/acceleration. If that solves your problem then the PSU could be a contender, but I wouldn't replace without testing.

I suffer "squirrel" moments on here and get easily distracted (this reply alone is an avoidance mechanism from finishing my control panel for my mill) - I can't remember if you've posted about your missing steps issue - if you have, point me at your thread. If not it might be worth opening up a new thread to try to resolve your real issue (just found your "Fountain of Knowledge" thread - but that ends without a conclusion).

Feel free to PM me if I'm going over old ground that's been discussed elsewhere - I don't want to take this thread off track.