I had the same issue with my hotpoint before christmas last year. First thing I did was remove the pipes from the soap tray feeder at the back and then aimed them into a bowl. With the machine programmed, I turned it on to see how much pressure was coming in. The cold feed was incredible, but the hot feed was only half. I removed the solenoid valve at the back and replaced it with a new one, which was very cheap. Bingo, full pressure again.
Apart from that, it has to be the holes where the dispenser tray goes. I use a safety pin every 6 months and clean out all the holes. It's a bit fiddly, but with the soap tray removed you can just about use a bent pin to clean them out. In the soap tray, at the back of the softener compartment there is a plastic cover I can remove, which contains a route for the softener. This also tends to block over time. Some softener just overflows into the soap compartment and the rest stays where it is. Just holding it under the hot water tap seems to dissolve the softener and open up the pipe again.
Before all this though, I would remove the hot water inlet, and look at the little mesh filter in the back of the machine. It may be blocked.