If your friend doesn't mind spending a few more dollars, I strongly recommend he replace the current counterweight with Express Audio's Heavy Counterweight. Not only does it weigh more (which will solve your need for a heavier counterweight), but it is a much better weight than the stock unit. Many of us who bought the Express Audio counterweight have been pleased -- even somewhat amazed -- at the improvement to the Rega tonearm's performance. I wrote a very positive review of this counterweight several years after adding it to my Rega RB-900 arm. You can buy the Express Audio counterweights (both the standard model, and the heavier unit) from Audio Advisor:
www.audioadvisor.com
www.audioadvisor.com