I take it for granted that you have checked the level of the power steering fluid reservoir, nobody would be that thick not to... So...
Has the car stood for any period of time?
Possible stiff steering column universal Joint (two of them) one inside the car and one attached to the rack and the stiffness will be in the position the wheel and angle they were left in. Rare on an Alfa but it can happen to SORN for long periods on vehicles and sales cars on the forecourt.
When was the last time the power steering fluid was actually flushed and changed?
Power steering fluid needs draining, replacing and bled every 24,000 miles or two years... If you don't know then it definitely needs replacing...Its a DIY job... Failure to do this leads to premature PAS pump and /or rack seal failure.
Using a turkey baster drain out the PAS reservoir as much as you can. Take out the securing bolts for the reservoir, twist it to either side to remove the securing clips for the feed and return pipe. Label the pipes "right and left" so you know which one goes where when refitting.
Lift the PAS reservoir out the way...
Arm yourself with a small funnel and a container for the old fluid (it's only a couple of litres in the rack and system)
Get a helper to turn on the engine and turn the steering lock to lock while you watch for the fluid escaping from one pipe (the return pipe)...
There is going to be a lot of load groaning and screeching as the system empties along with a really notchy feel on the steering until it gets really, really heavy to turn... This is all totally normal so keep going.
Once no more fluid comes out of the pipe... Turn off the engine... Refit the pipes to the PAS reservoir in the correct order and bolt it back to the bulk head...
2.1 ltrs of Dexron II power assisted steering fluid is what you need from any motor factor and not expensive.
Start pouring it in and get the helper to start the engine and start turning lock to lock again... The noise is going to be terrible at first (DON'T PANIC, IT'S NORMAL).
Keep topping it up as the helper turns the steering wheel and the noise will all of a sudden disappear and the steering should be light as a feather again... You have just drained, replaced and bled your power steering system... Congratulations
It took 15 to 20 minutes of your time!
You should look at the old fluid and compare it to the fresh, cherry red colour... The old fluid will have all sorts of gunk in it... The next words out of your mouth will be "No bloody wonder"