What year is your machine? The pre-millennium machines were 49mm and I believe the tamper I have that fits that basket is 49.4mm. The millennium machines have a 51mm basket, and I think a tamper of the same size fits, but someone please correct me if I am mistaken.
I have a 51mm for my La Pavoni Professional and the fit is snug. However, I am now in possession of a 49mm as well since I heard both will do....and...well, they both do. My preference, however, is for a 51mm. Andy
Sorry about that. I should have mentioned that my La Pavoni Professional is less than a month old. It's a post 1999 model and accepts 51mm tampers. The 51mm tamper is snug and doesn't push down to touch the bottom of the basket. Since it will always be filled with coffee it really doesn't matter. The 49mm tamper is not snug and can reach the bottom of your empty basket with a little wiggle room. That is why I prefer the 51mm.
No, if you are positive that it's a pre-millenium model you will stick to 49mm.
I took my portafilter and basket with me when purchasing my tampers. Living in Montreal, I have that option since there are plenty of places that sell them.
I don't know the year since I bought it used. The only thing a can tell you is that my LP ios a professional model et not the new millennium. Thanks!
Tamper size for 16 cup professionals and 8 cup europiccolas are the same, the size difference has to do with whether they are pre-millennium or millennium. See this thread to determine which model you have.