Is LP distortion the record or the cartridge?

Yes , the Lyra stylus cleaner is excellent and they supply it with a great brush. It is a bit pricey but IMHO worth it. Many styli are held on only by a gob of glue. Many solvents will attack the glue and then I think you know what happens. The Lyra cleaner will not attack the glue.

mglik has already discovered that his problem is worn records. Old records that distort like that are usually very dirty. So if you are going to play old or used records cleaning them thoroughly is crucial to the life of your stylus. I would play them with a less expensive cartridge that has a replaceable stylus Like a MM Audio Technica. I will not buy used records for this reason. I have seen enough to know you do not want to trust anyone else's record hygiene. 

Now that I remember could be a third possibility and this is the cable tonearm that some Triplanar owners warned that if it’s not in the precise rigth position will not " track " as should be.

This is not the case with the Triplanar FWIW but I have heard of this with some arms.

it can be challenging to set expensive carts. everything have to be spot on.  the more hi end the more demanding on setup. 

i suggest looking at setup video exhibition by Michael fremer. it helped us Alot.!  his article on compliance is on analog planet as well. 

supplementary reading whatever Peter of soundsmith explains. 

they cover everything need to know.