cartridge mistracks in final 25 of a record side

What arm/cart setting(s) are off when the cart mistracks in the final 25% of a record side?
Just a guess....anti skate...( just a guess )
Make sure that the arm isn't hitting the arm rest, (the small plate that raises and lowers the arm).
Also make sure the arm has enough travel.
The arm is a triplanar. It is not hitting the arm rest, and has enough travel.
I'm guessing they supply a mount to compensate for the offset.Otherwise,I would guess this could be a problem.

What do you mean when you say "the cart mistracks"? Is it jumping out of the groove? Staying in the grove but audibly losing groovewall contact? Maintaining groovewall contact but distorting? Does this happen on all records or just some? With all cartridges? Only a few? Just one? Has your setup always done this or is this a new phenomenon?

People are answering without sufficient information as to what's actually happening. As Sherlock Holmes repeatedly reminded Watson:

It is a capital mistake to theorize before you have all the evidence. It biases the judgment.
'A Study in Scarlet', Part 1, chap. 3

It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts.
'A Scandal in Bohemia'
Problem solved! It turned out that the tonearm wire was being pulled too tightly at the point where it left the back of the tonearm tube.

This was causing the tonearm to be pulled towards the outside of the record. This effect only would come into play towards the end of a record.

I created a little bit of slack in the tonearm wire and the problem completely went away.
So, it didn't have enough travel?
It had enough travel, but the tonearm wire was causing the arm to be pulled towards the outside of the record, like a strong anti-skate setting.