Welcome to the Forum!
I'm sorry to hear about your problem. Before you try moving the top up or down crawl under the trailer to check to see if everything is in the proper place, namely the hydraulic cylinder, the guide rod, and the safety bar. You said that the top had settled a few inches, that doesn't sound good. The safety bar should have been engaged and prevented that. There should be not sound when lowering which tells me there is something out of place underneath.
Here is the link to the Forum library where there are a bunch of manuals that have been put into PDF format. You may not find any manual that matches your 1991 Funchaser but look for one the comes close to 1991. The manuals are not model specific and are very generic.
http://www.hilotrailerforum.com/f49/
Hopefully you will find the problem.