Dear Alun: No, 21grs is on the high part of a medium mass, there are high effective mass tonearms in excess of 40grs.
Don't worry about before you mount and test the Celebration on it, after that you can decide if that tonearm is a good match to the cartridge and remember that the Jelco is a removable headshell design so you always can use not only a different headshell weight but a different headshell build material that can help to the Celebration shows at its best.
If you can change the headshell stock wires for the Ikeda S-50 that you can find through an ebay seller: 2juki, this sole change makes a difference for the better.
Regards and enjoy the music,
Raul.
Don't worry about before you mount and test the Celebration on it, after that you can decide if that tonearm is a good match to the cartridge and remember that the Jelco is a removable headshell design so you always can use not only a different headshell weight but a different headshell build material that can help to the Celebration shows at its best.
If you can change the headshell stock wires for the Ikeda S-50 that you can find through an ebay seller: 2juki, this sole change makes a difference for the better.
Regards and enjoy the music,
Raul.