Best cartridge for very old worn vinyl

@edgewear thanks for that !
I spoke with dealer and figured out how to move the arm on the Brinkman so hopefully will manage it in the next day or so.
Not being technically savvy I don’t profess to understand any of the physics at all...
The Brinkman alignment tool is based on the Dennesen alignment (?) All you do is fit it over the spindle, get one end lined up over the middle of the tonearm pivot and when all that’s in place you adjust the cartridge so that the tip of the stylus is in a small hole on the Brinman alignment tool. On that basis presumably the s2p doesn’t matter so much as long as you can adjust the cartridge in the headshell so it lines up on the small hole on the tool ?
Where I guess it might matter is if you can’t adjust the cartridge (like in SPU /FR7) ?
Again I’ve no idea what I’m actually talking about here, but if I’m able to adjust the FR 66 on the Brinkman that the FR7 is aligned properly on the Brinkman alignment tool,  then presumably that’s job done ? At that point does that also mean that the p2s distance will be “correct” ? if the answer to that is ”no” then it begs the question whether something like the Brinkman alignment tool actually aligns cartridges properly or whether ( if it does) whether the s2p is a critical factor ?

With same PS distance you can use 3 different alignmet methods by moving/twisting a cartridge in the headshell slots. Feickert protractor will give you Stevenson, Baerwald or Loefgren. Read more here.

With FR7 series or SPU you have to stick to the manufacturer’s method, for IKEDA it is Stevenson, you can’t twist your cartridge, because they are headshell integrated models, so any other alignment will be wrong for those types (headshell integrated models).

Some protractors are made only for one specific tonearm and you can’t use them for any other tonearm.

Feickert designed for any tonearm, you can use it on any turntable and any tonearm and it's up to you which alignment method you want to use (Stevenson, Baerwald or Lofgren).  

The Dennesen is a protractor, not alignment, the alignment is Baerwald
Denessen U.S.patent number 4,295,277 cites Baerwald (not Stevenson)

@chakster many thanks for that - so is this how I get the alignment right for the FR7/SPU cartridges?
1. Buy Dr Feickert Protractor.
2. Choose Stevenson alignment point.
3. Adjust FR66 with FR7 attached so that it aligns on the Steveson points.

If I use the Brinkman alignment tool (based on Baerwald alignment I gather) and follow the above the FR7/ SPU won’t be correctly aligned - is that right ?

Many thanks 
Howard 

Yes, Feickert is good to have for any situation.
First lock the PS distance recommended by tonearm manufacturer, then you will see that your FR7 or SPU will reach Stevenson point (step-1), for the step-2,3 you can rotate the protractor on the platter if needed. 

Baerwald alignment does not work for headshell integrated cartridges like FR-7 and SPU on Fidelity-Research tonearms. 

@chakster  thanks again.
Apologies for what might be dumb questions but my technical understanding hovers around zero on a good day ...
Supposing you could adjust either the FR7 or SPU in the headshell like most other cartridges. Would it then also be the case that only the Steveson alignment worked with them ?
What I don’t quite understand is this : a stylus, whether it’s in a Lyra, Koetsu or SPU (apart from having different shapes/lengths) does the same thing, ie sits in a vinyl groove and moves across from the outside to the inside of a record. It’s a mechanical operation.
If the stylus in (say) a Koetsu can work fine in (say) the Baerwald alignment  on an FR66 then why would the physical mechanics that enable the Koetsu stylus to get across the record well not also allow the stylus on an SPU to do the same (assuming the tonearm is adjusted so that the SPU is aligned in the same way as the Koetsu).
Best regards 
Howard