Mine definitely slows down at the very bottom of it's travel and I have used my foot to push it down on occasion. Didn't think much of it though....
I have one of the very common Harbor Freight floor jacks (steel, 3-ton, rapid-pump) and heh, just checked the manual about filling it.... As many know, HF has multiple versions of many parts. For this floor jack, they have (4) versions. I may have downloaded the wrong manual for mine. Three of them say
Add high grade hydraulic fluid (sold separately) slowly until the fluid reaches 1/4″ below the top of the Fill Port.
while one says
Add high grade hydraulic fluid into the fill hole slowly until the fluid reaches the top of the hole.