Vintage Dual 1228 Turntable : worth to upgrade cartridge ?


I have from my college days (1977) Dual 1228 with original fitted Shure M95ED cartridge .  It is maintained well , not used for about 20 years in between , but just cleaned , lubricated , resoldered some loose connections , etc and just runs great for me. 
I am not too much into analogue , so not planning to do big time investment into new TT , Phono preamp , but if  can get larger benefit by replacing the Shure M 95 ED with some new cart upto $ 200-300 , I would like to do it . 
My Phono preamp is very low end Cambridge Audio MM 551P . To go with new upgraded cartridge , I may even consider to buy used Phono with budget of $1000 . 
I would appreciate advice form FMs here , where I should spend my money to get most benifit on sound improvement . New cart , new phono ? 

radni
I'm glad to hear your happy, Bill sure is knowledgable with Dual.Happy listening!
rwmeditz, I feel happy that your efforts to restore your Dual TT paid off well. My experience has also been similar.
I had replaced the old stylus with a JICO ( Japan) stylus model
N95HE , cost me $96 plus shipping cost $15 , and got it delivered to me in less than 5 days. It sounds amazing! I was , initially, going to change the cartridge, but got some useful advice from this forum to first only change the stylus. And it has worked so well for me. I would suggest to consider to go for such stylus repalcement in future whenever it is right time for you.
BTW, website of JICO is worth visiting :
https://www.jico-stylus.com/index.php
Enjoy your Dual TT!
Thanks Radni, that's exactly what I did, replaced the stylus with a JICO. Looked into NOS, shocked at the prices, so went with JICO. So grateful for all the helpful advice from the community here.