Setting up an arm to be "parallel" with the platter (not taking into consideration the optimum VTA for the cartridge) can be a huge mistake.
Note: My SME is NOT parallel with the platter, nor have they rarely been, and its sounds really good.
Your non-improved arm with the original low-mass detachable head shell will have an effective mass of approx. 12.5 grams, which should be fine with the Hanna.
Amazing the advice you get from people with apparently zero knowledge (let alone first hand experience) with the SME non-improved arm.
If VTA is not the culprit, then cartridge loading would be the next thing to look into.
This will be my last post on the subject.
DeKay