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
Thanks for your responses . The verdict is quite clear about old Dual 1228. I will not do for upgrade of cartridge as not worth it. 
I will consider again if I am wanting to go into this serious business of Analog , and if I decide to go I will put a starting budget of $3000 for a new TT and cartridge , and further $500-1000 down the road for a used phono preamp . But I have to first make up my mind if  its my cup of tea. 
Thank you , ebm, orpheus10 and tooblue . 

Yogiboy,
will Shure M97XE be a good upgrade over my current Shure M95ED ?  M97XE is only $100 , so I don't mind buying it even if there is noticeable improvement . Will M97XE fit on my Dual 1228 arm ? 
Thanks 

radni,
I think the newer M97XE  will be an improvement over the older M95. Yes it will fit the Dual arm. What have you got to lose for  a mere $100 ?
I am with yogiboy. I would replace cartirdge, keep the cambridge phonostage, and save your money. Why spend more until your are convinced on commitment towards vinyl.  I have heard that phono cartridges age with time even if not used. This is first heard as a loss of bass.
Radni,

The 1228 is by no means the last word in turntables, but it's certainly good enough to get back into the vinyl game. My Dual 1229 is my
personal favorite and gets daily use. 

Get a new Shure, any Audio Technica or Nagaoka cartridge. 
You don't have to spend a fortune to enjoy vinyl playback. Properly set up the 1228 will  blow yhe average  CD player into the weeds. 

N.