NikL the teaching is still current as it has not been withdrawn so any old mag that makes the claim is proof unless a JW can show you that there is 'new light' on this teaching and there is none to date.
Still, they do have a problem with reading their own old literature. Therefore you can direct them to the Insight Book under mediator.
In part it states this
"Those for Whom Christ Is Mediator. The apostle Paul declares that there is “one mediator between God and men, a man, Christ Jesus, who gave himself a corresponding ransom for all”—for both Jews and Gentiles. (1Ti 2:5, 6) He mediates the new covenant between God and those taken into the new covenant, the congregation of spiritual Israel. (Heb 8:10-13; 12:24; Eph 5:25-27) Christ became Mediator in order that the ones called “might receive the promise of the everlasting inheritance” (Heb 9:15)"
Most JWs will argue that since they pray through the name of Jesus, he is therefore, without doubt, their mediator. However, the Insight book clarifies their position on this. Jesus has two roles, that of the mediator and also as High Priest. Basically, they say that Jesus acts as mediator through the New Covenant with spiritual Israelites (the anointed). When praying through him in prayer, he is acting in his role as High Priest and therefore both anointed and non anointed are able to do this.
The same Insight Book information under mediator states this
"There are, thus, others not of the 144,000 “sealed” ones who also pray to Jehovah God in the name of Christ, putting faith in the merit of his ransom sacrifice. This sacrifice is not only for those for whom Jesus mediates the new covenant but also for all mankind expressing faith in Christ. (1Jo 2:2) These not in the new covenant also appreciate that “there is not another name under heaven that has been given among men by which we must get saved.” (Ac 4:12) They, too, look to Jesus Christ as their great heavenly High Priest, through whom they can approach God and through whose ministration they can get forgiveness of sin. (Heb 4:14-16)"
There's a Youtuber, Bridget Azaz that called Bethel to confirm that this is still their current teaching and she was told that it is. There are some Elders who do understand their concept.