Portlight knobs & screens

This is really two separate issues:

1. Some of the black knobs that tighten the portlights on our 2005 IP 370 are cracked and not long for this world. Has anyone dealt with this? Is there a good source for replacements?

2. The Lewmar hatches on this vintage boat had screens and shades that rolled-up just like an ordinary, vertical window-shade, only horizontal. They no longer operate smoothly, and need some help. Either the hatch or the wooden trim would need to be pulled off the boat to get at them for a definitive repair. Even so, Lewmar doesn't have any replacement parts. What the lady said, not in these exact words but close enough, was, "This was a terrible design and we only used it for a couple of years. Good luck." So the question is has anyone had good luck with a work-around?

Thanks.

About the shades I don't know, sounds frustrating. But regarding the knobs I have had a few break. Fortunately the prior owner had a few spares. I thought if I run out I would use a thread gauge to match up some wing nuts for the portlight's and use those with silicon washers instead of the elusive and probably overpriced black knobs. . But if you find a source please post it.

The portlight knobs w/bolts are available from www.marinedepotdirect.com phone # 909-393-6100 for a cost of $6.18 ae. We have a 370 hull# 57 and had one cracked knob we purchased 4 ( 3 for spares ) as noted they come with the bolts attached. I hope this is of help Tom