I doubt the record weight will harm your table. I cannot comment how if will affect your sound.
I suspect your sound is compromised by the very large quality/performance gap in turntable and cartridge choice. The record clamp will not remedy that.
I'd advise you to pull the cart and keep it handy for when you upgrade your turntable. Rather than a clamp, invest in a cartridge with a performance more inline with that of the P3. Won't hurt to do both cart and clamp though.
I suspect your sound is compromised by the very large quality/performance gap in turntable and cartridge choice. The record clamp will not remedy that.
I'd advise you to pull the cart and keep it handy for when you upgrade your turntable. Rather than a clamp, invest in a cartridge with a performance more inline with that of the P3. Won't hurt to do both cart and clamp though.