LOZANDEBS

Hello there I'm hoping someone can give me some idea of what is causing this problem.... I have a PRM gearbox now if I cruise for a short time ie half an hour I don't have a problem but if I cruise for an hour when I turn round and select reverse ect its fine after this my box sticks in forward drive and I cant select neutral at all and if I go into reverse it stalls the engine. Its been doing this for a few weeks now and iv checked the oil changed the oil as well but still got the problem on longer cruising. After I moor up and leave it for a about half hour start her up and it frees itself and works fine again until I do a longer cruise. There is no nasty noises when its working only when its stuck until its frees itself again could I have a overheating issue ? Any help would be appreciated. Thanks in advance. Loz

We have just loined the site as we are new to boating.. we are about to purshase a 35ft narrow boat that is up at a private mooring at the top lock chorley a friend of mine lives on it at the moment. We want to move it near hyde to work on it as its mainley cosmetic work its an old boat but has its certificates. we are looking for a mooring near to hyde as i work there any advice on this would be appreciated. Thanks Loz Debs