Carl,
This is only a suggestion. Why don't you find a small weight and tape this to the bottom of the counterweight. This will work best if the counterweight is adjusted by means of sliding along the back section of the tonearm.
This way you can get the cartridge balanced and you can try out the tonearm. Being a unipivot it may not be the most suitable for the Denon which is a low compliance cartridge.
This is only a suggestion. Why don't you find a small weight and tape this to the bottom of the counterweight. This will work best if the counterweight is adjusted by means of sliding along the back section of the tonearm.
This way you can get the cartridge balanced and you can try out the tonearm. Being a unipivot it may not be the most suitable for the Denon which is a low compliance cartridge.