How should I proceed Glow-worm Space Saver boiler

I have an old simple Glow-worm Space Saver boiler. Until beginning of this last winter it has broken down once in 28 years when the transformer failed. I am more interested in reliability than fuel costs. Beginning of season it sooted up. I tried loads to heating and ventilating people but could not get anyone out. But once I had removed the soot it started to work again. Except about once a week the pilot flame went out. Flame looked OK and re-lit easy enough so changed the thermocouple in case but still the same. Then at long last I found a gas safe registered guy. He looked at it and told me to buy a pilot kit which he would then fit. But before I got one started to fail daily so I looked more careful and realised it only failed while running never when just on pilot so I stripped again and cleaned everything in case it was soot stuck in something causing the problem. Since then pilot flame has not failed.
Now I have a problem. As I said I want a reliable unit. Now it not so cold if I am to do anything now is the time.
1) Is there any point in my still getting this pilot flame kit?
2) Is it likely I have cured the problem or do I still need to do something?
3) If I replaced the hot water boiler which is a Main 7 with a combi boiler can I keep the old reliable glow worm as a back up?
I know if I use a water storage unit I can have multi-sources of heat all running at same time. But that is not what I want. I want to if the modern boiler fails to be able to switch it off and revert back to old faithful.
My family all have gas boilers all more modern than mine and all have failed with complex faults requiring printed circuit board changes etc. My old faithful has no printed circuit board so that can’t fail.
I realise that no one can give a 100% answer on this but some thoughts would be welcome.
One idea would be to install an electric back-up boiler as any break down on an electric boiler I can fix.
Had I found loads of muck in the boiler I would have no worries but I found very little wrong with it. Flame does seem more steady now but not completely steady still a little jumping with small non blue gaps between burner and flame. But before cleaning there were larger gaps between burner and flame and I was under impression it was snuffed out rather than blown out.
I am all ears.

Well time has ticked on and still the pilot is lit. Seems I have solved immediate problem. I still however consider that some form of up-grade may be prudent. However the balance between reliability and fuel usage is hard.

I think leaving the old boiler in place or fitting an electric one would be unneccessary and wasteful.

I would replace both boiler and water heater for a good quality combi, such as ATAG, Vaillant or Broag.

But as you have your exisitng boiler still working ok then do you really need to?

The fault you had is classic crap in the pilot injector

Seems I do as it failed again today. Only fails while running not when just on pilot flame which to me points to something wrong with main burners not pilot? The way it dances when running either the jet has worn and is now too big or the pressure setting on valve are wrong either way either specialist meters are required or gas safe card to get parts so I must look again for a gas safe guy to repair or replace it.

if the case was all sooted internally it maybe worth while getting the he cleaned .

ah the spacesaver couldnt find a more ironic name if they tried

Could still be partially blocked pilot injector.

When the main burner fires up it could be drawing the little amount of gas that is going through the pilot away from it.